Technical question regarding the aux input on the DJM-S9

Hi,
Do you know of an issue with the aux input having problems when being used with a drum machine (ie maschine)
When I use the aux input with this, or if I output programmed drums from ableton live, the sounds get cut, almost like they are being gated, but if I input via the line inputs or directly to my mixing desk they play correctly?
I'm hoping it's just a software issue as I'm limited for inputs, I've upgraded to the pioneer from my Rane, but the Rane doesn't do this on the aux input channel,
I thought it was maschine, or the pioneer drivers but after reinstalling all my software, and even after restoring my Mac to an earlier backup (pre DJM S9) the issue remained, I noticed today the ableton issue, but all plays fine via the headphones on my Mac too, so it's definitely the aux channel. (As far as my fault diagnosis goes)

Any help will be greatly appreciated

Regards

Mada