This is kind of the same fix as D1424, but reversed. Units can get stuck on passable navcells surrounded by impassable navcells because the short-pathfinder got them there, and then ordering them to move far way uses the long-pathfinder.
We can safely run a short-pathfinder call, using the same logic as in D1424, to get unstuck in at least some of those situations.
See replay:
Reported (by chance) by: Angen