In a part file, I had a shell feature with a wall of 1.6mm. Then I tried to edit it, adding a multi-thickness and choosing a surface. It didn't work for this geometry, and that's OK, but after I delete the multi face and the dimension I entered, SWX doesn't let me go back to a regular shell.  It keeps giving me this note.

How can I get out of this? Seems like a bug to me.

Rich