Sometimes I get ships that have some cargo space unavailable, even though it has no units loaded.
I noticed it happening when deleting units that are still considered "loaded". I guess the "delete unit" function does not check if a unit is in a transport, and therefore does not update the cargo capacity of said transport?
This could also possibly affect units that are traded via diplomacy (e.g. workers or siege units) that are also loaded at the moment of the trade, though I'm not completely sure.
Possible solutions:
-add a check to the "delete unit" function: if the unit to be deleted is in a transport, and if so, correctly update the cargo capacity of that transport after the unit is deleted
As a side note, when running Slavery and performing amphibious attacks, if there is empty space in the attacking unit's ship, slaves (workers) may still be captured, and the worker will spawn in the ship.