2012 Overland Summit, and yes I also have a clicking seat when my weight shifts!
The noise in my seat is definately coming from the upper seat back, not the lower seat or mounts. It occurs as my weight is transfered into the seatback as the vehicle moves. It sounds like some internal plastic seat components are hung up on each other and rubbing against each other until they "pop" past each other & I hear a click! Really not sure if I want some barely competent dealer tech removing my summit leather to poke around in my seatback to attempt a fix!
Should be a covered warantee issue, if you decide to let them attempt a fix though!