I had the same issue with my 2011 LTZ. I ordered the 60/40 bench seat. The 60 side would not power fold at times. You could hear the motor run and straining and when it did release it would pop. I also had to really slam it down to get it to latch so I could raise the seat back.
Took it to the dealer and it released every time but it was straining and had to be slammed down. They said it was normal.
I decided to try and fix it myself. I put the seat down without slamming and noticed one side would still move a little if I pushed down on it so it wasn't latched on that side. I pulled back the carpet, loosened the bolts on the mounting plate and placed a metal shim under the D ring where it didn't latch and tightened the bolts. This raises the mounting ring just a little. It now works perfectly every time without straining or having to slam it down to get it to latch.
I noticed on GM Techlink
http://enterthezone.net/techlink/wp-content/uploads/2012/04/april_techlink_2012.pdf a few months ago that GM referenced this problem and referenced a TSB for it. Scroll to bottom under Truck Issues. Not much information and I don't have access to TSB's but it did say the fix was a shim.
EDIT: Just read your post again and noticed you said the seat BACK. If this is your issue it is probably something else. Sorry.