Slot 1001

[el cid again]

Slot 1001 is hard coded to force a unit to be in hex 59/40 on certain occasions.

So are several other slots. But if you keep Tsushima Fort in its slot, or the fort in Pusan in its slot - no problem.
This is the case of Iki Fort - which is in the wrong hex in stock. The POINT of the three forts was to close the Tsushima Strait to surface traffic (or to force it to be shot at by 16 inch guns). So all three hexes had a fort - and all three need one. We have to use a different slot for the Iki fort to get there (Iki is right up against Kyushu - in the Kitakyushu hex - but Kitakyushu didn't exist as such - and should be called Fukuoka in WWII).