I loaded a previously developed project (GeocachersOnTheMove) to the new AI2-test environment. That worked just fine, much faster than in the "old" environment.
Then I saved the project under another name, GOTM, and that also worked as expected. After moving and replacing some blocks in the GeocachersOnTheMove app, I opened the GOTM developing area.
That now looked like it had been totally corrupted. Please look at the attached image.
FYI: Meanwhile I have used the emulator and imported the keystore.