While this mechanic is somewhat unpleasant, the actual bug is most likely not the changing of abilities between selecting the BO and the BO appearing in your assignments tab, but rather the fact that they change at all.

My guess is they were never meant to change in the "look at them and if you don't like it try again" manner. Which version would be preferable in the end is a different topic but I wouldn't expect a patch/fix to fully enable the "look and retry if you want" concept.