Had ours coming down like that, but ours was because they had cut the coroplast wrong and it didn't hit the metal frame some of the way across. I fixed it by screwing a door sill on there to bridge the gap. From what your pictures show I'd either put screws back in place with some fender washers or use the sill treatment. My problem is I can't identify what that is hanging down in the middle picture and that concerns me.
Dick, Joyce, Diego, Picatso and Gustav
2017 3720 RL, and 2013 HC 343RL
2017 3500 Dodge Maxi DRW 4X4, Pullrite Hitch, IS, Disk Brakes, 3rd AC, Winegard Traveler, Bathroom door mod, Dometic 320, couch for desk swap, etc.