It seems like you have a similar issue like described in this thread.
I will cut and paste the same answer and hope that it will be of help:
From what you describe, it sounds like you might need to adjust the endpoint settings on your transmitter, similarly to the Taranis setup document.
(Note that that document is written for the FrSky Taranis specifically, but you might get some ideas on how to make a similar adjustment on your radio).
Also, if the automatic stick detection gets it wrong during calibration, you can manually click the circle that you see is the correct one (instead of clicking 'OK').
Hope that helps.