Thanks for your answer. Is this behaviour new in 2.2.0? The exact same Kickstart rom that used to work in 2.0.1 does not work anymore in 2.2.0. In addition, the import says:
Kickstart import task started
Copy /Users/atlantis/fff/Kickstart 1.2 (33.166) (A1000) (Commodore) (1986) [!].rom
to /Users/atlantis/Documents/FS-UAE/Kickstarts/Kickstart 1.2 (33.166) (A1000) (Commodore) (1986) [!].rom
Adding ROM “Kickstart 1.2 (33.166) (A1000) (Commodore) (1986) [!].rom” to database (SHA-1: 6a7bfb5dbd6b8f179f03da84d8d9528267b6273b)
Import task is done
However, after that there is still no default Kickstart accepted.
On the other hand using the custom setting and choosing the same Kickstart file, I can start the Amiga, as I found now, thanks for the hint!