The seats both move well. They are power seats. The issue I am having feels like a bolt is loose on the floor or on the track, but none of those are loose at all. They are very tight. The seat rocks back and forth ever so slightly, and you can hear it "clicking" like it has loose bolts. The best I can tell, the bushings in the seat track that attach it to the seat itself seem to be worn.
The seat frame may have damage that you can't see without taking the upholstery off. Many years ago,on our 90 square body Burb, the driver's seat back frame broke, going down the highway. We were on a trip to Beaumont and Port Arthur at the time,and had Dad's big tool boxes in the cargo area. So he had me get them and brace the bucket seat back with them, against the second row seat, so we could get home. Then he pulled the upholstery off and welded it back together. Still holding when we got rid of the truck....
The seat had probably been making noise and moving a little more than it should,and we just didn't notice until it broke.
Not saying this is your root cause,but worth looking into. Never had it happen on another vehicle, but only takes one time for a wreck...