Unreal Engine 4.25 Rendering Issues on iOS (AR) / Crashes on iPhone

Hi all,

I have a strange issue with engine version 4.25 on iOS with AR. On Android this issue is not present and everything works perfectly fine.

The issue itself is hard to describe but here are some pictures:

Important to note at that point is, that the issue on the left only occurs when the objects are transformed (it doesn’t matter if it’s scaling, movement or rotation). My suggestion would be that it has something to do with the shadows, but I am really not sure. Could also be something completely different.

What have I tried until that point:

  • Sky Light: Toggled Cast Shadows

  • Directional Light:

  • Disabled all Ray Tracing related settings

  • Directional Light: Reset Cascaded Shadow Map settings to default values

  • Directional Light: Toggled Cast Modulated Shadows

  • Used Metal 2.0 instead of 2.1 and vice versa

  • “Mip Gen Settings” on textures used on that model:

  • Set to “No Mipmaps”

  • Set to “Sharpen 10” and other modes

  • Set “Texture Group” to UI

  • Enabled “Cook ASTC texture data for Metal on A8 or later devices”

  • Set “Environment Capture Prope” mode to “none” in AR config file (since I had issues with older engine versions with that)

So as of right now I’m running low on ideas how I could possibly fix that.

A few things to keep in mind:

  • That is an updated project from 4.22 (where I had no rendering issues)
  • The reason why I wanted to updated the project is that Apple is forcing you to build with SDK 13.x or newer
  • I’ve tested it on an iPad Pro 12.9’’ (2018), iPad 9.7’’ (2018) - same issues (iOS version 13.3)
  • On the iPhone SE 2020 the app directly crashes after showing the Launch Storyboard

So any help on that would be very much appreciated because I really need an engine version which is stable for both platforms (Android and iOS). In general I hope that Epic will give their AR mobile developer community some more love because since 4.20 I had issues with each engine version. The most stable being 4.22 I would say.

Shouldn’t read too much into it but at least it’s on their ‘roadmap’ in trello to give AR some love:

It’s probably worthwhile to ask Epic via if you haven’t already about your specific problem - I’ve not tried 4.25 yet:


thanks for the links. Yeah I’ve seen the info on the road map and that’s what actually still keeps me kinda calm.
But it’s still also worrying if you build your business around VR/AR solutions and having no exact road map.

I’ve maybe figured out what the issue was, but I still have to verify it. Will update here if it’s a success. Have to finish another project first.