Hell, at times the AI just seems oblivious to anything you are doing.
Because the AI did such a lousy job of R&D I play most of my games with everyone maxed out from the start. Otherwise I tend to end up miles ahead unless I slow myself down so I just cut to the chase to see what the AI will do in a balanced game.
I go to war with the Torians and I am playing as the Terrans. They started it by attacking a starbase with a group of ships that was not strong enough to wipe it out. They are rated the strongest faction in the game, I am like 4th because I build no Defenders at all.
I had a few fleets in the area that jump across the border to respond. I encounter nothing but defenders (a huge downer in its own right that should be corrected) sitting on planets waiting to be wiped out. It is a pain, as everything is fully updated, but accomplished in a turn or two. I invade 4 or 5 planets with the transports I had kept ready and start building up for a real invasion. I send my new transports to my old staging point on their border. A big mistake.
I had advanced a ways away from there. My combat fleets were at the front. They sent a powerful fleet of major warships around my flank, though another species territory and they appear back at the starbase, which happens to be right next to the 25-35 double troop transports I have assembled for an invasion. They attack the starbase. I try to run my ships away. I run right into another major fleet. I made a mistake and am being punished for it. They are all within a weeks travel from the enemy ships. They should be wiped out during the enemy turn.
So far all is well and good. But then they simply fly right by my transports and head back towards home. Those ships were totally unarmed and had minimal defenses. It would have been a slaughter and would have set me back a few months to a year in launching an attack.
Whatever happened it was bad. Either the AI did not see my ships because they didn't put sensors on their ships, or they saw them and did nothing about it.