// enforce color target is <= depth and MSAA settings match
if(RTTDesc.Width > DTTDesc.Width || RTTDesc.Height > DTTDesc.Height ||
RTTDesc.SampleDesc.Count != DTTDesc.SampleDesc.Count ||
RTTDesc.SampleDesc.Quality != DTTDesc.SampleDesc.Quality)
1. Compile a Debug Engine configuration
2. Create a new project and open it up in editor
3. Enable Forward rendering and MSAA
4. Close editor
5. Start editor again with a debugger attached
6. Start any level in VR preview
7. Editor breaks on a sample count check in D3D11Commands.cpp - function GetRenderTargetViewDesc.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-39304 in the post.