I am reaching out to see if anyone has had any luck with this when lubricating the tab/cam didn't work.
The 40% seat has been stuck up for almost 1 year in my 2016 Silverado. I have tried to lubricate it several times with both graphite grease and white lithium grease, neither worked.
Finally pulled my whole seat out this past weekend to ensure there was nothing unseen that was catching it or jamming it; nothing I could see was the issue. The dealership has quoted me ~400 to repair, there is no way I can pay that for something like this. As it is now I keep a flat blade screw driver in the door and manually operate the cam each time I need to let the seat down. Really disappointed with the quality of this truck and with GM's overall care for their customers.
UPDATE 4/19/20 I finally "fixed" the issue
After being so frustrated with this I "fixed" it by grabbing the seat cushion on the seat that was stuck and violently wiggling it back and forth until it essentially broke free and started working I am sure that what happened is that a micro amount of metal was sheared off the cam until the angles finally worked again. Again this is the "fix" I was reduced to unless I was willing to shell out ~400. At least I dont have to carry a flat blade screw driver around with me everywhere now to let up and down my seat.