I reset the save, sorry. Most of the outfit got removed, but the inner crotch and outer crotch stayed. I assumed it was intentional because a good drone is locked. Possibly it might have only happened once I got upgraded to S-Drone?
Viewing post in Release The Hypnodrones comments
Managed to get it to happen again, hth. https://files.catbox.moe/rsm7no.txt
I don't think it happened immediately on becoming an S-Drone. Might be caused by one of the studio chance events with Pink 386FA0?
https://litter.catbox.moe/uftqvg0yw10i78ik.json
Unfortunately still could not figure out why it happens, but I fixed the save for now (by forcing the undressing via a debug command). I tried a few events but none seem to trigger it for me.