These problems show up for me in the last update on Unreal Engine:
Access violation - code c0000005 (first/second chance not available)
UE4Editor_D3D11RHI!UniformBufferBeginFrame() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\windows\d3d11rhi\private\d3d11uniformbuffer.cpp:71]
UE4Editor_D3D11RHI!FD3D11DynamicRHI::RHIBeginFrame() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\windows\d3d11rhi\private\d3d11rhi.cpp:37]
UE4Editor_RHI!FRHICommandList::BeginFrame() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\rhi\private\rhicommandlist.cpp:1673]
UE4Editor!FEngineLoop::Tick'::
10’::EURCMacro_BeginFrame::DoTask() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3202]
UE4Editor!TGraphTask