I have a legitimate bug this time, and one that's a bit strange. At about the same time as I finished completely decking out my ship with underverse subunits (96 of them, that took a while!), most combat loot drops started to return just one item only, always an AI core. I'd say it happens about 80% of the time.
I can't say for sure if the two events are related, though, and the frequency can sometimes be inconsistent. I haven't been able to directly affect it by swapping out modules or anything.