DDJ RX Crossfader curve mode not working gradually

@Marek > Can you record a video to show exactly what's happening? By the way you describe it, it sounds like it's jumping from one side to the other.

unfortunately i can't record video because my laptop with rekordbox has broken down today and is in repair in this moment. However i'll try describe my problem in great details. Situation looks exacly like you said. Crossfader is jumping to end of the right or left side in my rekordbox but in fact is in other position. 

For example this is real position of my crossfader
And how it looks in rekordbox

Hello :)
my problem looks exactly like on this video
https://www.youtube.com/watch?v=0v3482elELo&feature=youtu.be
I hope that you know how to hel me :) !

@Marek > I know that's not your video, but that video also doesn't show the software mixer on screen, so it's hard to tell how the hardware is controlling the software fader.

ok i understand so when my laptop with rekordbox will be after repair i try to make my video with mixer section and software reaction on crossfader movement. ,

Same issue happened to me . The bug also affected  traktor and dj pro. 

Had to take the ddj rx to service and it returned in perfect working condition.

Check at the end of the ddj manual, there is a procedure to reset the controller. If that doesn't help, then have it serviced asap.