Output level from OutPut 1/2 is noe the same

Hi, I faced with problem of output level of my cortex.
the level of output 1/2 is not the same, it has 5 dB differets…a couple of week ago , it works correctly, but nit I should to do level of output 1 - to 0dB, the second output -5 dB, only in this set up I can recieve correct output level from both outputs.
the fireware is 3.0.1, the cortex was reseted to default setting, without deleting presets.
What’s problem can be here ?