Hi, I’m trying to troubleshoot a regression with VR in moving from 4.17 to 4.18 and am hoping someone can give me some guidance on where to look. I’ve posted an initial bug report to answerhub  but it hasn’t gotten any attention from Epic yet, so I’m trying to see if I can dig into the problem on my own.
Our project has been built to target the Vive and all of that is working great, and we picked up the Samsung Odyssey VR headset to give it a try. I know about the WMP branch of UE4 as a way to get support for Mixed Reality headsets, but for various reasons we need and want to stick with the main UE4 codebase from Epic. Fortunately, Microsoft and Valve have been working together to support Mixed Reality headsets via SteamVR, and in 4.17 this worked really well. Specifically, with steamVR beta installed, we could load up our project and both in the editor and in builds, it worked more or less equally well with a Vive or Odyssey headset.
For unrelated reasons, we’d like to upgrade to 4.18 (there are some non-trivial bug fixes we’d like, in addition to some new features in the forward shader renderer). When we load the project in 4.18, however, VR mode is rendered wrong - it’s as if each eye has a different camera and is looking at a different point in space or something, so you end up not with a 3D image but a headache and feeling sort of cross eyed. We found that this is true with our project, but also in UE4’s VR editing mode, in VR preview mode, etc. We even created a barebones project from the VR template and get the same behavior. So a plain VR project in 4.17 works great, a plain VR project in 4.18 gives the messed up rendering.
As I don’t know when someone from Epic will have time to investigate, I’m desperate enough that I’m going to start digging through the engine source code to see what changed to see if I can narrow down the problem more. But while I’ve spent a modest amount of time in UE4 source, I’ve never looked at any of the code related to VR, so I’m wondering if anyone has some suggestions as to where I should look, especially if the above description triggers any thoughts that might narrow down my search. Really, any suggestions or guidance would be very much appreciated.
Thanks in advance!