Either the Rustoleum wasn't thoroughly dry, the 2K stuff not adequately compounded, and an incompatibility of the 2K stuff to anything enamel. You should have just went with the 2K stuff and forgot the 2X Rustoleum clear. It's kind of redundant even if it did work. I don't recall ever hearing that the Rustoleum 2X is worth using at all.
Type at you later,
Dan McEntee