Some feedback now that I've found the solution to my troubles and the Zap green has turned my failures into professional (in my opinion
) PE jobs and I use the Zap pink where I need it to float more.
Huge thanks for the tip John and others!!!
I've also started to clean my PE parts much thoroughly with iso before gluing, but if that was part of the solution, or the problem, I don't know, but my PE parts are now sticking in place and especially the Zap green is fantastic to use on small PE parts since it's not runny.
In case someone searches for CA glue and PE in the future, here's the answer!