You have my sympathies, Appalachian. Personally, I wasn't planning to play again until Crusade comes out, but the way this issue crops up again and again -- since the release of the base game, afaik -- is somewhat disheartening. If it's still a problem when the expansion arrives, I'll likely hold off until I'm certain it's been nailed down.

I, for one, don't want to invest several hours into a new game only to discover the ai's ability to fleet up is on the fritz, yet again.

Seems to be a very elusive bug. Brad mentioned it even in the last stream and said he would look into it, but since the bug is around a very long time now we'll see if he finds something

Principally from an outside view it looks very easy to do, something like that (much simplified):

if (ship or fleet movement ends) {

   if (ship or fleet is on hex with another ship of fleet of the same faction that has already ended its movement) {

      if (combined logistics don't exceed current maximum) {

         combine ships to fleet

      }

   }

}

I can understand ships not fleeting up if they meet accidentally in the middle of going to a distant target, but not if they are stationary. But I must say I myself didn't see that behaviour very often, so I cannot say for sure whether the stacked ships I saw were stationary or not.