TLDR: carriers using the 1st fighter type originally worked, now the fighters just fly around the enemy ship without firing.
There is another long-time bug in the Battle Viewer that shows Support Ships (and their defending Guardians) at the front of the fleet, despite the fact that they are actually at the back of the fleet. Is it possible that the Battle Viewer just made it look like your fighters were next to the enemy ships? If you click on one of your fighters, and one of the enemy ships, what were their roles? (Interceptor, Assault, Guardian, Escort or Capital)
In my current game I began experimenting with carriers (the previous times I'd tried them they were bugged). Built a couple of carriers, stuck an escort ship with them, and sent them into battle. They easily destroyed a larger enemy fleet.
Carriers have a bug that was only fixed in one of the recent patches. I was told that the fix is only applied if you have the patch AND you start a new game when running that patch version or higher of the game.