Minecraft Retractable staircase hangs on one side - sticky piston

I've build a retractable staircase. But, on the right side, the sticky piston stays in the open position. Does anyone know why?

I've made a demo replica of your construction, in all possible orientations:

I can't imagine what can be wrong in such trivial design. Do you have the latest Minecraft? Any mods installed? Any redstone wiring/torches underneath the staircase?

UPD Changed the video, the old one is here.

You seem to be the victim of the piston update bug. when large contraptions update the pistons do not seem to respond. (if you look up Captiansparkles on youtube he runs into the same problem in one video) try building the same contraption in another place and see if it works or a different set of pistons refuse to update.