Some of my formgels were kidnapped. I reformed them after they had already been taken off the map, now they have one by one randomly become members of other factions. I have no way to convert them back to my colony, so their afterlife caskets are just decoration now.

They also gave a mood debuff to the other colonists, i.e. "My wife was taken" "My son was taken", which is really funny when they're literally talking to each other.

Anyways, probably a bug.