Hi Gunter,

re:
> Just tried that and you're right it works but would still like to get to the bottom of the problem!

It looks like a bug in the conversion to ACIS geometry, I've added it to my list to investigate.


> Also, now I'm trying to fillet the inside of the ring and the same problem is happening:

It looks like you can get the inside ones done for now by switching the "Library" option inside the Fillet command options to "Library: Solids++".

- Michael