I know this is an old thread, but this just happened to me, and I figured it out.
***Sticking occurs when the lower pull cord does not fully retract.***
There are 2 pull cords on the seat back.
1. The lower pull moves the entire assembly up against the driver/navigator’s seats to fold or, back up to seating position.
2. The upper pull controls the seat-back to fold back and forth, to flat.
My lower cord needed to retract another 1/2”, which freed the upper cord.
To make the lower cord retract, I pulled it out lightly then just it let go when it felt like there was some tension. This made the spring pull it in. Took a couple tries, but you’ll know when it pops in.
Hope this saves someone a bit of frustration. Thought I was going to need to pull the seat apart.