First take a really good look at that left pop that’s sticking. Make super sure that it’s put together right with no parts that could bind or pinch. Check the switch adjustments for that pop, too. Make sure everything opens and closes as it should through the range of motion of the pop. Check the diode. If that’s all good, look really closely at the wiring and see if you can find a short, especially something that might be shorting due to movement. If you can’t find anything at the left pop, follow the wires from that pop looking for potential shorts for other things in that row/column on the switch matrix.
Sorry if you covered any of all of this in your video. I couldn’t watch it with sound because it’s the middle of the night and I don’t want to wake others in my house!