I could probably point out a couple bugs in ACIS shell also if you are digging into that part and want/ready to hear.....

Just reproducing Toms object with a sphere can lead into a couple that may point to something....

Create a sphere of radius 12. Stretch it down with edit frame to look like Tomes object. Shell it 1 inch. Try to cut it in half with a Boolean diff line front plan. Spin 180 same result. Spin 90 cuts.

Delete outer shell with a drill down selection before spinning. cut solid in half. Attempt 1 inch shell on half.