Hello @it.bb and @Benutzer6294, welcome to the NVIDIA developer forums.
First of all, this thread might be interesting for people to check how to address some issues with DLSS and VR in UE.
Regarding Frame Generation the bad news is a detail i had nearly forgotten:
VR is not supported with DLSS framegen mostly since framegen uses a dxgi swapchain to present frames to a window. But VR uses a completely separate runtime to present images to an HMD.
In the thread linked above and some other discussions there have been thoughts about how to workaround this, but natively with our plugin this is not possible.
Which does not mean that we should crash and the crash issue is taken rather seriously and looked into right now.
I hope to get some update soon.