FWIW from our internal MAS 200 4.5 PU 4 system.
The inventory maintenance Cost Detail tab contains two hidden columns for Lot and Serial Number. These columns are supposed to appear for as appropriate for either Lot or Serial items. After installing PU 4, these columns do not appear, unless you drag the line between the Description Header and Receipt Date to the right. Resetting the panel did not help. the problem exists in all companies.
I tested on a MAS 90 test system at 4.5 PU 3 and the lot and serial columns appeared as expected. I applied PU4 to this system and the columns still appear as they should.
So far, just MAS 200. So far, I don't have any clients on PU 4. We try to eat Sage's (or our own) dog food first. I don't really know if this is a MAS 200 issue, PU4 issue or something stupid I have done.