I have noticed that the Git version control feature works on Windows but does not seem to initialize properly on MacOS. I get the following error messages for the same UE project on my Mac.
Error fatal: Not a git repository: '"PathToProject/.git'
Error You should check out a working copy into your project directory.
All these statements are wrong though. The folder is there and is working with any other external Git front-ends.
The problem is in fact that my Git Plugin could not work correctly under OSX with UE4.7 (up to 4.7.5).
There was a bug in the Unreal Engine regarding the Mac Platform that I fixed a week ago :
https://github.com/EpicGames/UnrealEngine/pull/920
That fix was merged onto master on commit 2196a60
(duplicate of [4.7 Preview 5] Git doesn't work with existing repository - Programming & Scripting - Unreal Engine Forums and [4.7.2] Problem activating GIT support (bitbucket) - Programming & Scripting - Unreal Engine Forums)
Problem should be solved in upcoming UE4.8