# Lumen Broken Flickering Reflections UE5.4 **URL:** \ **Category:** Rendering\ **Tags:** unreal-engine, Lumen, Rendering\ **Created:** [June 14, 2024, 9:35am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836 "2024-06-14T09:35:00Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 14, 2024, 9:35am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/1 "2024-06-14T09:35:00Z")
I’m having issues with glass and mirror reflections in my scene. I’ve tried applying all tips I could find in tutorials and forum posts but nothing seems to help. Any idea where I might start looking? ---
**Author:** ![comlys](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/comlys/32/998665_2.png) [@comlys](https://forums.unrealengine.com/u/comlys)\ **Post date:** [June 14, 2024, 6:24pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/2 "2024-06-14T18:24:06Z")
This glitchiness could be drivers. If you are on the latest NVidia drivers can you try and roll back? ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 16, 2024, 11:32am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/3 "2024-06-16T11:32:18Z")
Hi @comlys, thanks for the swift response. I just checked and my drivers were actually slightly out of date. I updated them to the latest version (Studio Drivers for RTX 3090), however, the issue persists. Do you have any further ideas on what I can try? ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 17, 2024, 8:15am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/4 "2024-06-17T08:15:52Z")
Not sure if it’s much help but this is what my Lumen Overview looks like: ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/9/3/c/93cfcb07df9ef15ec47d99b89b3d4d06af132dbb.jpeg) Does this show any aparent issues? ---
**Author:** ![comlys](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/comlys/32/998665_2.png) [@comlys](https://forums.unrealengine.com/u/comlys)\ **Post date:** [June 17, 2024, 5:18pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/5 "2024-06-17T17:18:34Z")
Unfortunately, I’m not sure. I haven’t seen anything like that yet. Can you try disabling screen traces? ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 18, 2024, 6:33am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/6 "2024-06-18T06:33:30Z")
@comlys I just gave disabling Screen Traces (GI and Reflections) a try, but that didnt help either ☹ ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 19, 2024, 9:31am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/7 "2024-06-19T09:31:04Z")
Would you know who might be able to help? I’m not sure if this is a UE5 bug, a driver issue or something that can be fixed with CVAR’s. As mentioned above, I was already on a previous driver version and updating to the latest studio and game drivers both didnt help. I’ve tried all reflection/lumen related settings I could find but nothing helped here either. Disabling lumen reflections and setting it to screen-space did indeed help, but I need lumen reflections for obvious reasons. Unfortunately i dont have any other machines where I could test if it’s hardware/driver related. I’d appreciate any insight you or any of your collegues might be able to provide. ---
**Author:** ![glitchered](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/glitchered/32/768299_2.png) [@glitchered](https://forums.unrealengine.com/u/glitchered)\ **Post date:** [June 19, 2024, 10:59am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/8 "2024-06-19T10:59:24Z")
the artefacts on the dashboard look like z-precision artefacts blender exposes when the near clipping distance is too short. not sure what your interior geometry looks like. the rear mirror could be the same issue. if it’s 5.3 or 5.4.2 i could test it on my craptop (with old stable drivers). you’d have package the map and car in a functional project, tho. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 19, 2024, 12:03pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/9 "2024-06-19T12:03:48Z")
I’m using 5.4.2. I have packaged the project and have just uploaded to Google Drive: Please let me know once you have downloaded the file. Please let me know if this works for you. The project has DLSS enabled, i’m not sure if that causes issues should you not have an NVIDIA RTX GPU. * * * Additionally, if you have any tips on sorting out the loading screen I’d be greatful as the project doesnt seem to be loading in the background while my current loading screen plays. ---
**Author:** ![glitchered](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/glitchered/32/768299_2.png) [@glitchered](https://forums.unrealengine.com/u/glitchered)\ **Post date:** [June 19, 2024, 12:46pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/10 "2024-06-19T12:46:16Z")
okay. i get the same artefacts. glitching mirrors and dashboard. not as frequent tho. but it’s there. i reckon it’s a content or setup issue. no debug console available. this is not much of a troubleshoot i could do. you could try a different shadow method or check your camera settings. to my eyes it looks like a shadow or precision thing. the glitches appear in specific areas that are seperate geo or decals and it’s mostly shadowed areas or edges. gpu is a 3060m with driver version 536.67 for the technical info. performance is not great on it. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 19, 2024, 12:57pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/11 "2024-06-19T12:57:54Z")
I appreciate you giving it a look! At least it seems to be UE/Project related, right? ---
**Author:** ![glitchered](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/glitchered/32/768299_2.png) [@glitchered](https://forums.unrealengine.com/u/glitchered)\ **Post date:** [June 19, 2024, 1:00pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/12 "2024-06-19T13:00:53Z")
yes. very likely not the driver. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 20, 2024, 7:21am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/13 "2024-06-20T07:21:48Z")
@comlys I noticed you requested access to the file yesterday - have you been able to access and review the packaged application? Have you been able to gather any more intel on the matter by any chance? I created a completely new material for the mirrors (Reflection 0, Metalness 1) to ensure it’s not material related, but I received the same reflection issue. It therefore seems to be render-setting related, from what I can tell. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 20, 2024, 7:33am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/14 "2024-06-20T07:33:16Z")
Somethign worth mentioning - the reflection issue only occurs when inside the vehicle. Maybe that bit of information might help. Here are my Project Render Settings ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/5/9/f/59f415557b86336f64c6fbf0be92390e4545d914.png) Here are my PPV Lumen Settings ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/7/f/3/7f313884f24145bda17daccd9dc082ca81cad145.png) ---
**Author:** ![comlys](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/comlys/32/998665_2.png) [@comlys](https://forums.unrealengine.com/u/comlys)\ **Post date:** [June 20, 2024, 6:27pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/15 "2024-06-20T18:27:58Z")
Not from a packaged build no. If its was a UE project I could look at it further. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 21, 2024, 9:17am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/16 "2024-06-21T09:17:26Z")
I’m happy to provide you with the full project. I have/will send you an invitation to your Epic Games email from which you should be able to access the project (it’s currently uploading, might take 2-3h)(EDIT: upload complete). Let me know if you can access the Zip file (15GB in size). As the project contains some 3D files that are somewhat sensitive, I would like to request that you make sure not to redistribute any of the files found in the project. I’m very eager to hear if you find any issues in the project that might be causing the problem as this is the final hurdle to me finishing this demo project! * * * A word of warning - i’m not a game developer and am self-taught when it comes to UE (I have a 3D animation background in Maya/Blender), so some of the game logic might not be optimized. A lot of stuff is triggered via the UI UMG Widgets. AFAIK the only external plugins used in the project is DLSS from NVIDIA. ---
**Author:** ![comlys](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/comlys/32/998665_2.png) [@comlys](https://forums.unrealengine.com/u/comlys)\ **Post date:** [June 21, 2024, 9:28pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/17 "2024-06-21T21:28:13Z")
RT refractions or switching the material off of Thin Translucent to just a DefaultLit/Translucent material fixes this (and renders more accurately). But I cannot get the Thin Translucent to calm down. Honestly, I have a complicated relationship with ThinTranslucent materials, ha. Let me ask around and see if this is just a limitation or if there is a magic cvar. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 24, 2024, 4:02pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/18 "2024-06-24T16:02:00Z")
Thanks a lot for looking into it! It’s been a busy few days so I haven’t had the time to try out the fix myself yet, but I’ll look into it tomorrow and will report back! ---
**Author:** ![comlys](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/comlys/32/998665_2.png) [@comlys](https://forums.unrealengine.com/u/comlys)\ **Post date:** [June 24, 2024, 6:03pm UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/19 "2024-06-24T18:03:02Z")
I talked to the automotive team here. What they do is they have inside and outside glass objects. Lumen still has issues with reflecting on the backside of a thin translucent object. ---
**Author:** ![Grimgorkos1](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/grimgorkos1/32/551445_2.png) [@Grimgorkos1](https://forums.unrealengine.com/u/Grimgorkos1)\ **Post date:** [June 25, 2024, 5:00am UTC](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836/20 "2024-06-25T05:00:35Z")
@comlys just so I understand, the inside and outside glass objects, are they one-sided geometry or solid meshes? E.g. would simply separating my current pane into 2 saparate geometries (removing the outside edge/border) solve the problem regarding thin translucent reflections? I’ll give all of your suggested options a try later, thanks for the info! [Next page](https://forums.unrealengine.com/t/lumen-broken-flickering-reflections-ue5-4/1902836.md?page=2)