Hi Jfs, I've got a fix for this set up for the next v5 beta.

You can also apply the fix to the current v5 beta by updating with the attached file Extrude.htm .

Put the attached one in place of your current one which will be something like:
C:\Program Files\MoI 5.0 beta May-22-2022\commands\Extrude.htm

Does that hopefully fix it?

Thanks,
- Michael