WEIRD bug with OffsetSrf

I sell medallions that i 3D print. I model them by making a paraboloid, projecting my vector art onto it and then using OffsetSrf command, to make the medallions 1,3mm thick.
Today, this happened when i used the OffsetSrf command:

This has never happened before, but now it does, even after re-launching and doing the process over.
Any ideas?

It can be difficult to diagnose a problem using only pictures. A .3dm file with geometry makes it easier for someone to help you.

You can upload a .3dm file with sample geometry using the vertical arrow icon above where you type a post. In Windows you can also drag the file to where you type the post. I don’t know if that works on a Mac.

Include both the geometry before OffsetSrf and the geometry after OffsetSrf.

Try the SrfSeam command on the srf prior to offsetting it into a solid. Move that edge away from the trimmed edge of that circle cutout, then offsetsrf. If that doesn’t help, upload the 3dm file with that single srf.