Pass through latch for seatback
I think you're right. I believe that something has gotten disconnected (or broken). I sat in the back seat bouncing against the seat back to see if I could free it up, but no luck. (Luckily no one was walking by!! I looked pretty strange)
I'll try some of the other strategies you suggested.
I was hoping someone would say, "There's a little wire that is hidden under the watchamacallit, just tug on it and it will release the latch."
Thanks! At least I have one seat that lays down!