I also use a case-sensitive file system on a Mac, and was getting this crash too.
To anyone else having this problem, look for error message in ~/Library/Logs/Unreal\ Engine/Editor/UE4.log
In my case, the error was: Couldn't load shader file 'LpvDirectionalOcclusion', which is located at /Users/Shared/UnrealEngine/[version number]/Engine/Shaders/.
I had to rename LPVDirectionalOcclusion.usfto LpvDirectionalOcclusion.usf (i.e. change the “PV” to lowercase), and that fixed the “filename not found” crash.