If you are running from source then try walking up the chain of functions originating from the error PipelineStateCache.cpp line 238 and see in which area it fails.
is it during the RHI validation stage?
I’d put a breakpoint at PipelineStateCache.cpp line 1967
static FGraphEventRef CreateGraphicsPipelineState(....){}
and step through the code and see where it fails. You can at least track down the exact point of failure. I’d help but I’m still on win 10 here.
The 5.1.1 hotfix does mention a fix
UE-171261 Valid PSOs are filtered out from manual PSO cache
You error likely us linked directly to PSO (Pipeline State Object) which is the part that seems to be effected by the crash.
Perhaps updating the source files for the engine might fix it?
Full list of fixes