So I'm not sure how this bug comes about yet, but in short I have had two occasions today where a soldier has "mutated" into the mercenary technician "Slug"(?); the one you get from the Kaos marketplace. They retain their name, skills, and equipment (sans armor), and are not proficient with their new permantly equipped tech arms.

Their personnel screen is also bugged out. Once you land on it, the skills UI freezes up, and does not refresh when switching to another soldier. Doesn't throw any exception.

I've also had the personnel screen whack out and show the Mutoid options, as well as a bunch of unresponsive UI that NEEDS TEXT. Once this happens the geoscape breaks.

Again, not sure how this triggers. I'll update if I figure it out.