Herelink Controller Joystick vs SBUS

I’ve calibrated this controller multiple times but can’t figure out how to solve the discrepancy between joystick input and SBUS output. You can see in the linked video that there is several mm of deadline in each direction at the ends of travel. Is there a way I am not finding in the documentation on how to fix this?

https://youtu.be/AET9mZ3oBSk