I've killed all of the infiltrators in the sector where the escorted ships start going in circles but the mission log still said I haven't killed one of them. Had to abort the mission.

https://imgur.com/a/ChKIOCb

The infiltrators in that mission are exceedingly annoying, in that they like to turbo around you in circles, and sometimes they do that outside of your radar range. I suggest disabling your background temporarily, and looking for the telltale thrusters where nothing is on your radar.

I don't think that should be expected behavior. Especially because I don't think it always happens like that. Sure, bots might spawn pretty far out due to the sector's designated jump vectors or whatever controls mission bot spawns, but *normally* the bots will at least drift towards you.

If you look at his screenshot Luxen, the bot indicated WAS killed, so not a range problem, but more like a stuck mission problem.