So I discovered that the GoaperDemo and my project have the same problem under 4.19.
isMoveCompleted only seems to return true once for the first completed move request. After that it seems to never return true.
In GoaperDemo They get stuck in PickupAmmo, and in mine they get stuck in a MoveToTarget action, which is doing pretty much the same thing as PickupAmmo.
Hope this isn’t a bug in 4.19!