Adjusting Default Light Settings for Atmospheric Fog causes Crash

Adjusting default light settings in the Color Picker palette for atmospheric fog causes the engine to crash in UE 4.12 Preview

Regression: This does not occur in UE4.11

1. In UE4.12, Open Blank Blueprint Project Template
2. Select Atmospheric Fog in the World Outliner
3. In the Atmospheric Fog Details Panel, open the Default Light Color> Color Picker palette
4. Adjust color by using R, G, and B sliders in the Color Picker palette
   RESULT: Editor crashes 4/4
   EXPECTED: Fog color adjusted without crashing

UE4Editor_Renderer!InitAtmosphereConstantsInView() atmosphererendering.cpp:324
UE4Editor_Renderer!FViewInfo::FViewInfo() scenerendering.cpp:381
UE4Editor_Renderer!FSceneRenderer::FSceneRenderer() scenerendering.cpp:1422
UE4Editor_Renderer!FDeferredShadingSceneRenderer::FDeferredShadingSceneRenderer() deferredshadingrenderer.cpp:126
UE4Editor_Renderer!FSceneRenderer::CreateSceneRenderer() scenerendering.cpp:1688
UE4Editor_Renderer!FRendererModule::BeginRenderingViewFamily() scenerendering.cpp:2026
UE4Editor_UnrealEd!FEditorViewportClient::Draw() editorviewportclient.cpp:3311
UE4Editor_Engine!FViewport::Draw() unrealclient.cpp:1148
UE4Editor_UnrealEd!UEditorEngine::UpdateSingleViewportClient() editorengine.cpp:1713
UE4Editor_UnrealEd!UEditorEngine::Tick() editorengine.cpp:1460
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() unrealedengine.cpp:368
UE4Editor!FEngineLoop::Tick() launchengineloop.cpp:2772
UE4Editor!GuardedMain() launch.cpp:148
UE4Editor!GuardedMainWrapper() launchwindows.cpp:126
UE4Editor!WinMain() launchwindows.cpp:200
UE4Editor!__scrt_common_main_seh() exe_common.inl:264
kernel32!<Unknown>
ntdll!<Unknown>