Inconsistent Channel 3 output

Hello,

I am facing a curious behavior on channel out 3. To point out that problem: i have set both channel 1 and 3 with GroundSteering function while moving left/right pitch stick as shown in this video
Only channel 1 is following stick input but channel 3 is totally inconsistent.

My RC_MAP is:
image

Is it a hardware failure on channel 3 ?