Something I've noticed while I have my Vasari Fleet, led by the Loyalist Titan, attacking an enemy planet. I leave them to attack as they wish and do building and research elsewhere. When I return the Titan and one other capitol ship is bombarding the planet, but the other ships that can attack the planet itself are in formation a short way away from the planet and are not attacking.

Save file: http://www.mediafire.com/?n2ly9mwbyp501ss,inv81od794kjqv9

As of this save the Loyalist titan is attacking the planet, the other capitol ships have no other target and are not assisting with attacking the planet until I specify the planet as a target.