I don't know if bleach will strip paint. Resin is a different material than plastic. DO NOT put resin in brake fluid to strip paint. I'm told this will nearly melt resin. Possibly Purple Power or similair will take the paint off.
Bleech White or bleach will remove the mold release agent from resin parts. This release agent acts like grease when it comes resisting paint. This could be your problem-the release agent used on the resin.
Do the instructions say anything about cleaning the body and/or what with?
Try to get more input on what to strip the paint with. Resin kits/parts are good but usually pricey.