Multichannel Proxies - synced Clips - the selected preset does not support the audio channel type

So many questions about proxies here, but I found no real solution so far.

Usually in other NLEs, I can just throw any video at it, select proxy->prores, and it just works, no matter which audio configuration. 

Now after playing with audio settings for an hour, I am afraid, I cannot get it to work properly in Premiere at all.

I synced my video files to audio for a mixer via Timecode in Tentacle Sync Studio.

It combines audio with passthrough video.

This way I get two audio streams with ten audio channels in total.

Four audio mono streams from my FX3 recorded internally and one with six channels from my mixer.

When I convert it to prores proxy with 10 mono streams it works.

Then I try the ZV 1.

It has one stream with 2 channels - so a stereo-configuration.

With those six mixer tracks added its a total of eight.

I cannot find a proxy setting that works, for example using eight mono tracks or four stereo gives me just the error message:  

"the selected preset does not support the audio channel type"

Is there anything I can do?

Is there ANY setting that converts video with audio pass-through?

Thats would be such an easy thing to do.

Or is it better to convert externally with ffmpeg for example with pass through audio and reconnect in premiere?