Saw these UEF drones trying to repair fatty mobile factory. Somehow, it has HP, and it can get damaged, but not repaired, so the drones get stuck trying to repair it forever.
UEF engi stations "repairing" mobile factories
https://replay.faforever.com/21548340. It's the Holly Raid mission.
00:59:30 - top fatty's mobile factory is damaged by mercies
01:15:00 - falling czar damages bottom's fatty's factory
01:29:00 - drones start getting stuck trying to repair bottom fatty's factory
Strange. Tried replicating in a custom game with cheats, didn't work.