First off - NEVER leave tape on "a few days" !! , take it off carefully ( by slowly pulling it over itself ); the longer you leave it, the more chance for the tape glue to react with the paint below, ( which probably was be still gassing out- the paint solvent evaporating; as in your case here ) ........ again, the best / easiest way to tell if your paint is cured, is to smell it; if there is a smell, let it dry until there is none; then do your taping. anyway - let this dry a couple days & try Ronson lighter fluid, it works - but be gentle; put a tiny amount on a piece of T shirt cloth & it will do the trick; first test it in an inconspicuous place to be sure it's fine with this paint. - good luck.
BINGO ! Good old cigarette lighter fluid DOES work , I've used both Ronson and Zippo brands .