-diff on UE4Editor.exe starts projectselection

Okay pretty sure i am doing something wrong.
What i want to do is, start the BluePrint-Diffing from commandline (for example to be used in Git).

However it seems UE4Editor.exe does not react to the commandline and simply opens the projectselection. Has something changed, compared to 4.10?(Never used it before but all guides/articles i found are from this version)

as for version 4.15 you need to specify the project path.

UE4Editor.exe %FullPathToProject.uproject% -diff [options] left right