1. I had a fleet of capital ship and a titan phase jump to a sun, trying to get to a planet on the other side. Most of the ships went around the sun like i normally see, but three of the ships went under the sun, all at different angles too. This of course slowed down the departure time of the entire fleet.
Yeah fleet movement still needs some slight improvements, but the dev's are working on it they said (check Yarlens known issues thread).
2. When my titan used its Disruptive Matrix ability i couldn't see anything happen. The ship used the ability (the cool down bar was full) but the normal green bubble was not there. I was in normal viewing range (not to far out). I didn't move the camera at all and the next time that the titan used Disruptive Matrix i could see the green bubble. Not sure whats going on there.
Well sometimes when a lot is happening on the screen at once (also don't forget the game's background processes in later game stages), not all particle effects are shown in order to improve game performance. If all particle effects were shown on the screen your video card would probably fry in larger battles. This is most likely why you didn't see the ability particle when your Titan activated Disruption Matrix (this particle effect is quite heavy compared with weapon particle effects for example).
3. I think i saw this issue in at least one of the other feeds, but here is it again. one of the AIs capital ships was not using any of its abilities. It was a carrier that had over 350 Antimatter points, but the ship never used any abilities (the antimatter meter never changed).
This is probably a bug. I have seen it happen too in my last game (an enemy Marza class Dreadnaught was just holding position in one of my gravity wells without firing at anything in it's weapon range, nor using any abilities. Needless to say it got torn to pieces by my turrets and Starbase).