Hello! I checked and un-checked literally everything in my attempt to find what is wrong. I was just changing an option in the stereo layers, then tested, then again. I am pretty sure I did them all until the project started working and saving so I don’t remember anything specific. I am pretty angry myself I don’t have a clear solution. What I remember is that I ended up having my stereo layers setup exactly the same way I had them when the problems were present, so I didn’t change anything.
It appears there were some changes made to stereo layers from Epic (if I remember correctly the layer shape menu is different than in 4.24, has that steamvr option now), so maybe what I eventually did was re-construct my stereo layers by ticking and un-ticking everything. The next thing I would try is to completely erase them and make them all over again. Unfortunately 4.25 and 4.26 introduce many changes and bugs (one of them being we can’t resample the terrain anymore, clearly an omission) and also, UE5 is on the way. So I expect a bumpy road ahead! Sorry I’m not very helpful, I hope you find your way out of this mess!