A lot of the AI only ships lack the AIOnly tag in the ShipClassDefs.xml. This means that ships that are supposed to be exclusive to the AI are also playable by the human player, and increases the number of ships in the shipyard list. But on the other hand a number of ships that are supposed to be usable by the player does have the AIOnly tag while they shouldn't.

Because of the large number of ships where this tag is wrong i am not going to list them all here.

Furthermore because of another erroneous AI tag in the ShipClassDefs.xml, all the support ships seem to be classified as transports for the AI.

Fix:

find in the ShipClassDefs.xml file the ships that have

<AIShipClass>Transport</AIShipClass>
<StrategicIcon>Support</StrategicIcon>

and alter this to

<AIShipClass>Support</AIShipClass>
<StrategicIcon>Support</StrategicIcon>