I have the same problem. Sometimes it goes away when rebooting the controller once. Sometimes it takes multiple reboots before it clears out.
I tried calibrating the sticks, and it looks when I do not touch the sticks, there is a slight movement captured (-3) on the screen.
I suspect there may be a glitch with my controller due to how I store it in the DJI fly more bag. The space there is too fit and probably the sticks remained pushed for long periods of time. Although I used a plastic cover to keep them in place.