Sorry, I just got to this. This is a verified issue, and in fact it was fixed in v23 just a little while ago (I don't track every ticket so wasn't aware). I was unable to reproduce it (I use v23) and so installed v22 and indeed if Feet and Inches is the active selected unit there is occasionally an error in Volume and Surface Area, so you are not crazy.
The workaround for now is to use another unit when performing that physical properties calculation. The automated test plan that tests this part of the product was failing ungracefully and silently at a point near this test component, which has also been addressed.