Update: Noticed it was an .xml typo. Under ShipClassDefs.xml The iridium and other battleshipD class have the typo.
...
<InternalName>IridiumBattleshipD</InternalName>
...
<BlueprintDef>DestroyerDBlueprint</BlueprintDef>
Should be
<BlueprintDef>BattleshipDBlueprint</BlueprintDef>
Of course their may be more to it than this 