Weird MIDI channel behaviour with Polybrute and PB Connect in Ableton Live

[rrr123]

I'm confused by something that's happening in Ableton Live 11 (on Windows 11) with the Polybrute and Polybrute Connect.

The Polybrute is configured to send MIDI on channel 4 (and channel 5 for lower, but I'm not using a split). I have verified with MIDI-OX that the Polybrute is indeed sending notes out on channel 4.

I have a MIDI track in Ableton Live with Polybrute Connect on it, and this is set to receive on "Polybrute MIDI" on "All Channels". The Polybrute and Polybrute Connect are communicating fine in both directions. The notes I play register in Polybrute Connect as expected, and I can send data from Polybrute Connect to the Polybrute.

I also have another MIDI controller (Arturia Keystep) that sends on channel 1, and another MIDI track in Ableton Live which receives from "All Ins" on "Ch. 1". On this track I have a VST synth (Arturia Jun-6 V). Now I would expect my Keystep to play this VST synth, while the Polybrute minds its own business.

But when I play on the Polybrute keyboard, the Jun-6 V synth plays. Somehow that track is receiving MIDI on channel 1 from the Polybrute even though the Polybrute is sending on channel 4. If I switch the Jun-6 V to receive on "All Ins" and "Ch. 4", it receives nothing, even though that is the channel the Polybrute is sending on.

What is going on? Is Polybrute Connect somehow echoing the MIDI it receives back out on Channel 1? Or how else could the Polybrute's MIDI be arriving on channel 1 after being sent on channel 4? (Again, I have verified using MIDI-OX that the Polybrute is indeed sending MIDI on channel 4, not channel 1.)

I'll attach a screenshot of the setup in Live.

[StudioDeutz]

There is an issue with the MIDI channels. And Arturia knows it - a ticket was opened...

You need to rethink the MIDI setup - I did too.

On page 64 of the English Connect manual you can find this hint. It seems, that it affects not only split mode:
"When PolyBrute Connect is active and the PolyBrute is played in Split mode [p.47], USB MIDI send
and receive channels are fixed at 1 for the upper part and 2 for the lower part. This improves Sequencer/
Arpeggiator performance when using Splits."

See thread: https://forum.arturia.com/index.php?topic=108973.msg190885#msg190885

[rrr123]

Thank you. I was not using split mode when testing, so this issue does indeed seem to be the same one as in the thread you linked.