Still happens with the UM changes.
I agree with leper above, the diagnostic is first that some units in INDIVIDUAL.RESOURECERETURN.APPROACHING can't get in-range of the storehouse as there are other units in the way, and these aren't part of the same formation since locally these are individuals.
Possibly then going back in formation is also buggy.
This is tricky to fix - keeping units to have the same obstruction group when in individual orders seems dangerous (attacking?), making units go to the next waypoint not in formation when they deposited would fix the stuck-ness but not the formation behaviour.
Possibly we should add an intermediate order to go away from the store-house in these cases?
Alternatively unit Pushing would likely fix this.