Your bars are a little wide but I doubt that they is your problem. With bars too wide you just wind up with combs across boards, not a pile in the bottom of the hive. Sounds like heat. Whats the temperature like in your part of TN right now?
I would make the bars smaller and stop waxing them. Use wedge strips or Popsicle stick starter strips on the bar, unwaxed. The bee's can attach the wax to the bar better then you can melt it on there.
My TBH's are made from plastic barrels. Hot melt glue won't stick well to the plastic. Can easily remove it with my finger, no nail required. Melted bee's wax won't stick well the to plastic. Again easily removed by pushing on it with my finger, no nail required. But the bee's have occasionally attached brace comb to the plastic barrel. Even with the hive tool that stuff is hard to remove, likely due to the curvature but it sticks.
My theory is that you had comb up on the bars and the wax you put on the comb melted and the combs dropped.