Had an evil AI ship crash and 3 scythers 4 centipedes popped out. A few days later, 36 wargs showed up and went straight for the mechanoids (instead of my nearby fleshy colonists who were outside farming).
Best part: the mechanoids didn't fight back. At all. They were all slaughtered without firing a single bullet. The wargs didn't attack the AI ship, however.
Caveat: This happened on a game that's running the superior crafting mod. But since the bug is related to factions (and not crafting), I'm reporting it here because I doubt it's caused by the mod.
I can attach a savegame if requested.
Come to think of it, I just remembered that on the same map, a different evil AI ship sent out a psychic wave and drove a nearby rabbit insane. The rabbit went on to attack a centipede (again, the centipede didn't fight back) and nearly killed it before the rabbit calmed back down.
Apparently Mechanoids do everything in their power to kill sentient beings, but they feel nothing but love for animals.
Sounds like the Manhunter AI doesn't like the mechanoid one, I'll see if I can repro this on vanilla later.
Will investigate thanks.
Fixed!