I have a file which my model space units are cm, layout space units are inches (we are building in metric, but a lot of the design is being done and proofed here, so printed imperial sized paper). My dimensions are primary units are decimal (and a cm suffix) with a length factor of 1. My alternate units are Feet & inches with a length factor of 100/254 (0.393701).
This issue I am seeing is that the alternate units are off by a factor of 2.54 when placed (the dim will read 100.0cm [1’-3 1/2"] instead of 100.0cm [3’-3 1/2"]), but will update if I change anything in the dimension properties (for instance, if I change the precision from 1.00 to 1.000 and hit OK the dimensions will update to the correct alternate units). If I set alternate units to decimal, still keeping the 100/254 length factor, the alternate units seem to place fine and don’t need to be updated. So this seems to only affects fractional alternate units.
It doesn’t seem to matter what the layout space units are. I changed them to CM to match model space but am still seeing the bug.