Suburban third seat stuck one side is latched other side is not.

Question moved from Seat (Spanish Car maker) to Chevy.

Brute Force. Get in through the passenger side and roll down the window. Have a friend hold the door latch open. Lay across the front seats and push with your feet. Have another friend take video and be famous when it unlatches and your friend goes flying. :>D

Inspect the seat belt material for damage and replace if necessary.

do you have the owners manual ? check for any object that may have got into the locating latch a small stone would be enough to stop it engaging/locking in place

I just ran into the exact problem with my 2004 Suburban. Once I got the seat to lay down all the other mechanisms worked as they should and I could get the seat in and out as usuall. I found this post below which explained how to get the seat down. Wish I could take credit for figuring it out on my own but I can't.
"After working on it for a couple of days here is what I did to remove the 3rd row seat.
On the rear lower right and left side there are plastic covers, if you push the seat material forward a little you can see a hole where a nut holds it on, remove the nut. On the left side pull back the plastic cover and you can see the wire and the lever that releases the seat. With my foot holding up the #1 release lever on the right side I used an open end wrench to push forward the left side lever and the seat folded down.
I then used the #2 and #3 levers to remove the seat.
To view the whole cable, open the lower seat cover, it is an overlapping plastic clip, My problem was a loose cable, similar to a brake cable on a bicycle, after fixing it I have had no problems."
To remove the nut I used an 8mm socket wrench. My problem was not a loose cable but the #1 mechanism wouldn't pull up all the way, I'm guessing because that left side locked in out of order. I pushed that left side lever down with a hard tool and had my 5yr old daughter pull up on the #1 and the seat folded right down.
Hope this helps if you havn't already gotten it fixed.

We had this problem once as well. We discovered that if all 4 latches (two in front and two in back) are not closed completely the seat back will not come up. In our case we had to lift the seat enough for the latches to close even though they were not connected to the floor and then we were able to unlatch and relatch everything so that it worked properly. The key is to take a very close look at all the other latches and figure out if they are locked properly. If not then that is your problem.
hope this helps.

Trip all three rear latches - the ones that are not tripped prevent the release levers from releasing

I really don't think your going to find an answer here. You have something bent ,jammed or some foreign contaminant wedged in it.
You need someone to actually look at it and figure it out. We can give you a bunch of maybe's like I just did but thats about all we can do.

I solved the problem by spraying WD40 into the front side of the seat support that was sticking. This support has a rubber closure to protect the mechanics of the seat. After spraying a generous amount of WD40, I waited about 5 minutes and tried the lever to fold the seat. It worked and still does.

first open your rear hatch/doors.2nd fold third seat over buy using latch on right side. 3rd pull relase handle in middle of seat on the back bottom . this unhooks the back latches. use the other hand to pull meatl bar up, tipping seat. 4th while holding metal bar with the one hand use the other hand to pull small release strap. it is too the right of the metal bar, this releases the front latches, pull rearward the seat moves out. the seat is heavy good luck

I drive a 2008 Suburban LT and my company has a true work "fleet" suburban. The only difference between these two that I have is the back of the fleet vehicle has a thick rubber mat in the back with no seats. After removing the black mat I found that the channels and rods that the rear seats clip into are present. The third row seats are installed by clipping them in no bolts or tools are required.