I had this happen on my 32RLS right after I purchased in 2021. I contacted Alliance about the issue. They told me that there was supposed to be an aluminum backer in the wall for the screws to bite into. I tried larger screws but no luck. Based on their direction I purchased some bulb tite rivets and reinstalled the railing. It's been on there for almost 5 years with no issues. You can google the rivets, but they are an exploding type of rivet. The ones I got were more substantial than the tri-fold shown above.
My &0.02,,,had this happen on a previous tow behind. Used the large cap “exploding” pop rivets. They come in different sizes,,,have engineering on pullout.
Many original screws had been over tightened by drill & were stripped when purchased,,,replaced all,,,caulked each rivet hole prior to install & rivet caps after completion & recaulked top of mount a top line exterior caulking,,,took on 3 5,000 mile Oregon to Texas & back trips,,, never had a problem again,,,but was a mfgr/dealer recommendation at that time! Good luck👍🌞🍀!!
Trailer did have metal backing behind fiberglass wall @ awning mount One consideration w Lager screws & thru bolt solutions allow easier future removal than rivets.