Power Liftgate Doesn’t Work When It’s Sunny

Our 2015 QX60 has a strange issue. If it sits in the hot sun for long enough, the rear liftgate stops responding to either the key fob, front button, or rear button. You press any one of those and absolutely nothing happens. If it clouds over or we park it in the shade, it will start working perfectly again once it cools off.

Any suggestions? I am game for disassembling it but don’t know where I should be looking.