I think cross roads knows more about it then camping world. The plywood under the membrane is suppose to be fastened to the rafters. Either stapled, screwed, nailed, and possibly glued along with one of the fore mentioned.
If it is in fact the plywood bubbling up, and it was mine. I would get some eternabond tape, cut it open, screw it back down and apply the tape.
Or if you don't want to do it yourself, find a reputable dealer that you can trust and pay them to do it.
2008 Cruiser CF26RK
2013 Ford Eco-Boost
Heavy duty payload - Max tow