Had this same problem. I got it working again by copying a few lines from the 4.22 branch into 4.23. In ‘WindowsMixedRealityHMD.cpp’, you’ll see a comment “// Then finally try to load the WMR Interop Library” and the error message is right after that. Before that comment, around line 174, add this:
FString PerceptionSimulationDLLPath = EngineDir / "Binaries" / BinariesSubDir / "Microsoft.Perception.Simulation.dll";
FString HolographicStreamerDesktopDLLPath = EngineDir / "Binaries" / BinariesSubDir / "HolographicStreamerDesktop.dll";
void* PerceptionSimulationDLLHandle = FPlatformProcess::GetDllHandle(*PerceptionSimulationDLLPath);
void* HolographicStreamerDesktopDLLHandle = FPlatformProcess::GetDllHandle(*HolographicStreamerDesktopDLLPath);