So I have replaced a motherboard only my PS4 pro controller and found the same issue. I took a touchpad from my other ps4 pro controller and that seemed to be the issue. There are a couple of videos on YouTube of ppl showing some small fixes such as resetting the controller and switching between two controllers. After attempting those fixes with no result, I decided to swap touch pads, when I did that the issue was apparent. More than likely your touchpad is defunct/damaged from disassembly or wear and tear. Recommend trying the swap if you have another controller (preferably of a similar model), this will give you the info if you need to replace the touchpad.