You didn't mention if your seats have the memory function but from how you describe the situation I'd suspect that's what's up.
I had a similar situation when I bought a set of 2006 Porsche 911 seats. The issue on the driver seat was that it had a memory function so you could preset seat positions for up to three different drivers. I found a plastic box with a circuit board panel mounted under the drivers seat. What I figured out was that this box communicated with a body control module which I of course didn't have, or want!
I got lucky though. I took the seat to the local Porsche shop where I found a guy who was into hot rods. He took the time to pull out the wiring diagram and sort out how to jumper around the circuit board so the seat worked like the pass side.
Hope this helps.