I don't have any firm idea why Olive seems to have changed from entirely Zone Free to entirely Zone A locked. I do know that it's not exclusive to Olive. The "revised" BRD of Patton from Fox is Zone A locked but the Wild River BRD from Fox is Zone Free.
It may be Region A locked because some other recent Olive BRDs have been. But don't go by what DVD Beaver says because according to him every Olive BRD is locked - and most of them are not.