I just tried 5.1 Preview 2 and same issue. It looks like this issue was not commited. I have exact same issue with the error: Assertion failed IsInGameThread() (File:MyPc\UnrealEngine-ue5-main\Engine\Plugins\Runtime\Steam\SteamVR\Source\SteamVR\Private\SteamVRHMD.cpp] [Line: 1581]