I don’t have a mutant brain, but looking at the settings page here, maybe could offer a couple suggestions to try. It looks like in the Gate Outputs settings, you have Gates 1-4 with settings “note input”, and Gates 5-8 set to “Midi note”. And it is set up to take note input on the CV Outputs as well. So it may be that on the Mutant, if you are trying to sequence note’s/melodie’s, then you only get do 4 channels of that. 4 CV parts, and 4 Gate parts set to complimentary settings.
But, I you were just trying to trigger gates out of the gate outputs, say for triggering drums, that is a different thing. If I were to just test the gate outputs 1-8 on the Mutant, I would make sure all DT Midi tracks are set to midi channel 13, and in the Mutant Gate settings 1-8, I would set each to Midi note, and define a different note for each Gate. Then in the DT, set each channel to its corresponding note, NOT1 setting, and sequence each track to test it out.
So I guess it all depends on how you are using the Mutant. What is your use case that you are trying out here?