Found another bug, it seems. When a crane has a target ghost and is already holding item for said ghost, it keeps the item in hand when ghost is removed. It then either locks up and doesn't do anything until rebuilt, or goes to work on other ghosts in range while keeping the old item in hand, now holding 2 items in hand during work.
Reproduction: Put down ghosts, give crane resources, remove the ghosts while crane is in transit with the item.
Edit: This seems to happen at random when multiple cranes work on the same area. Most of the time they go for separate ghosts, but I assume sometimes their targets overlap and when one does the job first, the others get into this condition.