Unity does not create iOS Xcode Project

Hi,

probably someone encountered the same problem. Yesterday I updated to macos sierra, and now my Unity does not create Xcode projects for iOS any more. It does neither report an error, but just tops at "Compiling" and then returns to the build screen.

Any hints? Xcode is the newest one, 7.3 (7D175), so is Unity (5.4.1f1).

Regards
Clemens