So, this is actually two separate little bugs.
Bug 1: When a capital ship is are queued up, that fleet cap displayed for them is in the fleet supply info card is 50 + (Supply For All Active Caps). This weird total doesn't include past capital ships, just active ones, (checked by scuttling a few caps). Easiest way to replicate is to quick start and rush a second cap, it will show as "Queued" with 100 supply.
Bug 2: When a Titan is queued up, it doesn't show up as a queued ship in the fleet supply info card at all.