Every time I open material editor in my VR project (Instanced stereo on, forward shading on), I get this in my output log:
[SPOILER]LogOutputDevice: Error: === Handled ensure: ===
LogOutputDevice: Error: Ensure condition failed: !ReflectionCaptureBuffer.IsBound() [File:d:\build++ue4\sync\engine\source\runtime\renderer\private\BasePassRendering.inl] [Line: 89]
LogOutputDevice: Error: Stack:
LogOutputDevice: Error: [Callstack] 0x00007ff95ac19878 UE4Editor-Renderer.dll!<lambda_546f5d4d09c7ed88ec9f1c978fd02c6c>::operator()() [d:\build++ue4\sync\engine\source\runtime\renderer\private\basepassrendering.inl:89]
LogOutputDevice: Error: [Callstack] 0x00007ff95a4e66c2 UE4Editor-Renderer.dll!FMeshPassProcessor::BuildMeshDrawCommands<TMeshProcessorShaders<TBasePassVertexShaderPolicyParamType<FUniformLightMapPolicy>,FBaseHS,FBaseDS,TBasePassPixelShaderPolicyParamType<FUniformLightMapPolicy>,FMeshMaterialShader,FMeshMaterialShader,FMeshMaterialShader>,TBasePassShaderEleme
ntData<FUniformLightMapPolicy> >() [d:\build++ue4\sync\engine\source\runtime\renderer\public\meshpassprocessor.inl:85]
LogOutputDevice: Error: [Callstack] 0x00007ff95a4f2cd4 UE4Editor-Renderer.dll!FBasePassMeshProcessor::Process<FUniformLightMapPolicy>() [d:\build++ue4\sync\engine\source\runtime\renderer\private\basepassrendering.cpp:971]
LogOutputDevice: Error: [Callstack] 0x00007ff95a5205e1 UE4Editor-Renderer.dll!FBasePassMeshProcessor::AddMeshBatch() [d:\build++ue4\sync\engine\source\runtime\renderer\private\basepassrendering.cpp:1505]
LogOutputDevice: Error: [Callstack] 0x00007ff95a9f54f3 UE4Editor-Renderer.dll!FRendererModule::DrawTileMesh() [d:\build++ue4\sync\engine\source\runtime\renderer\private\renderer.cpp:264]
LogOutputDevice: Error: [Callstack] 0x00007ff962f77340 UE4Editor-Engine.dll!FCanvasTileRendererItem::Render_RenderThread() [d:\build++ue4\sync\engine\source\runtime\engine\private ilerendering.cpp:394]
LogOutputDevice: Error: [Callstack] 0x00007ff962fe513f UE4Editor-Engine.dll!FCanvas::Flush_RenderThread() [d:\build++ue4\sync\engine\source\runtime\engine\private\userinterface\canvas.cpp:722]
LogOutputDevice: Error: [Callstack] 0x00007ff95b9b52a5 UE4Editor-GraphEditor.dll!FPreviewElement::DrawRenderThread() [d:\build++ue4\sync\engine\source\editor\grapheditor\private\materialnodes\sgraphnodematerialbase.cpp:235]
LogOutputDevice: Error: [Callstack] 0x00007ff956e8ecf4 UE4Editor-SlateRHIRenderer.dll!FSlateRHIRenderingPolicy::DrawElements() [d:\build++ue4\sync\engine\source\runtime\slaterhirenderer\private\slaterhirenderingpolicy.cpp:1262]
LogOutputDevice: Error: [Callstack] 0x00007ff956e95c9c UE4Editor-SlateRHIRenderer.dll!FSlateRHIRenderer::DrawWindow_RenderThread() [d:\build++ue4\sync\engine\source\runtime\slaterhirenderer\private\slaterhirenderer.cpp:817]
LogOutputDevice: Error: [Callstack] 0x00007ff956e9e130 UE4Editor-SlateRHIRenderer.dll!TGraphTask<TEnqueueUniqueRenderCommandType<FSlateRHIRenderer::DrawWindows_Private'::29’::SlateDrawWindowsCommandName,<lambda_076ca5c89cb03ad0d8e3fd21b4a903a2> > >::ExecuteTask() [d:\build++ue4\sync\engine\source\runtime\core\public\async askgraphinterfaces.h:842]
LogOutputDevice: Error: [Callstack] 0x00007ff970c022d8 UE4Editor-Core.dll!FNamedTaskThread::ProcessTasksNamedThread() [d:\build++ue4\sync\engine\source\runtime\core\private\async askgraph.cpp:686]
LogOutputDevice: Error: [Callstack] 0x00007ff970c02563 UE4Editor-Core.dll!FNamedTaskThread::ProcessTasksUntilQuit() [d:\build++ue4\sync\engine\source\runtime\core\private\async askgraph.cpp:582]
LogOutputDevice: Error: [Callstack] 0x00007ff9816659e1 UE4Editor-RenderCore.dll!RenderingThreadMain() [d:\build++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:333]
LogOutputDevice: Error: [Callstack] 0x00007ff98166c174 UE4Editor-RenderCore.dll!FRenderingThread::Run() [d:\build++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:464]
LogOutputDevice: Error: [Callstack] 0x00007ff970ff4b0f UE4Editor-Core.dll!FRunnableThreadWin::Run() [d:\build++ue4\sync\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:96]
LogOutputDevice: Error: [Callstack] 0x00007ff970ff0877 UE4Editor-Core.dll!FRunnableThreadWin::GuardedRun() [d:\build++ue4\sync\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:53]
LogOutputDevice: Error: [Callstack] 0x00007ff9abdf4034 .DLL!UnknownFunction ]
LogOutputDevice: Error: [Callstack] 0x00007ff9ad433691 ntdll.dll!UnknownFunction ][/SPOILER]
EDIT. Fixed: Unreal Engine Issues and Bug Tracker (UE-74673)