VERY INTERESTING FINDING:
After a clean system re-install from scratch, every application new installation, all checked.
The compressor finally worked again, but inside FCP on the time line Happy beach balling as before.
Thinking the project file itself is corrupted, try to export as XML – it didn’t work – froze on export.
UNTIL:
I had a lot of markers, also on the clips in the timeline, after deleting all the markers, suddenly it worked.
I did not know, but apparently to many markers on timeline freeze FCP down.
You never stop learning, and all the fuzz I did…and the solution was so easy 🙂