I am updating leadership positions for a Scouts BSA troop. I’m finding that Scoutbook will not accept leadership positions from its own pull-down menu if the scout is also registered in another unit (in this case, a Venturing Crew). It acts like it’s attempting to validate the position against the Venturing list instead of the Scouts BSA list. Those positions that appear in both lists (like Historian and Den Chief) are accepted.
Another possible data point: The Venturing Crew was the latest unit joined, and so appears first in the scout’s membership list.