I’m using 4.7 Preview 8 (Launcher) and it seems creating Macro Library is impossible.
Repro steps:
1: Create a new Macro Library in Content Browser.
2: Press Enter to apply your name.
3: Crash. 
I’ve attached log and dmp file.
This is already fixed in the 4.7 branch on github.
Great to hear that. Hope it will be available in Preview 9. 