We had this same issue with our elkridge, and then the big horn. I contacted the factory as both of our units were new at the time. The factory originally thought maybe they had gotten some soft screws(china), but pretty sure they were just over torqued, when installed and the heads were barley hanging on, before they popped off. On my rig it was the screws on the the sides of the as the slides popping off their heads. I think the flexing of those slides, when going in and out was causing the stress on the fasteners. After a while they stopped breaking off.
I went and bought some stainless screws on my own and simply replaced them as they snapped off. Putting them in next to the OE screws as there is no way to get the old ones out after the heads broke off.