I've no idea if anyone else is getting this bug, but in a couple of game sessions I've had my destroyed frigates and cruisers still count in my fleet supply. This has only been a problem with TEC so far, I haven't actually checked if it happens with advent since I've only used capitals in games playing as them since they were added to the Beta. It also doesn't seem to happen until well into the game, as my early game scouts didn't remain in the fleet supply when destroyed.
Another bug is enemy AI players not expanding if they have been trapped behind pirate bases. Even if I destroy the bases to let them out, the AI refuses to capture new planets.