I have the same problem. I have a project with multiple audio channels and I want to export them as individual channels in a MXF-file.
Method:
When I created a new sequence I choose "Multichannel" from the "Tracks" page. When I export the MXF OP1a, I choose 8 channels from the "Audio" page. None of the channels are muted.
Result:
The rendered file contains 8 channels, but only the first two channels contains any audio (main left + right), the rest of the channels are empty. Channel 1 and 2 contains the audio from all channels, but I want the channels to be seperated in the same way as they are layered in Premiere.
I don't understand your answer to wleoni75's question. Could you please help me further?