Behr DeckOver is a special product - four times thicker than traditional stains. Like any finish, prepping the surface really is key to making it stick. With respect to this particular product, though, prep is even more integral because of the thickness of this coating.
To answer your question, there's unfortunately no way to patch the problems you're having with this finish. If it's not sticking, it's not sticking. If you were to repair just those loose areas, no doubt other areas will eventually loosen up, too.
Removing this product will be tough, though. On Behr's website, they explain that removal of DeckOver requires multiple application of stain and finish stripper, and will likely also require a scrubber, scraper, power washer and/or sander.
I wish we had better news, and wish you the best with the project.