Output offset in simple mixer does not work

Hey guys,
I am working on PX4 firmware for a differential drive rover. My main problem is that the output in my simple mixer does not get any impact from the output offset value at all. An example of my mixer is:
M: 2
O: -20000 20000 -XXXXX -10000 10000
S: 0 1 8889 8889 0 -10000 10000
S: 0 0 1111 1111 -YYYYY -10000 10000

The output is the PWM value to control a brushed motor. I have another output to control the direction of motor rotation.

My main problem is that this value -XXXXX does not have any impact on the output.

Any help or advice would help me a lot and thank you in advance for your support :slight_smile:

Note that I have tried even without S line to see if I can see the offset in the output like this:
M: 0
O: -20000 20000 -XXXXX -10000 10000
still no impact on the output from the offset. I get impact from the scalers and the interval boundaries but not the offset of output.
I even get impact from the offset of inputs (-YYYYY) but not the outputs (-XXXXX).