Not sure if this is an import or export bug. If you open the file “Front Support.stp” it imports correctly. Now export as a stp file and re-import, the small spherical dimples have extra parts not trimmed away.
Next I tried exploding the part, delete the 2 extra surfaces then shrink all and rejoin. Export again then import the I get the extra surfaces again, partly trimmed away but still there.
I think this is an export problem because I sent the file for 3d printing and they had the same problem. I don’t need any help working around the problem, this is just a bug report.