I think you just triggered the solution in my brain.
Channels 1-5 for scene 1 are:
1. Kick
2. Snare
3. FTom
4. Tom1
5. Hat
Channels 1-4 for scene 2 are:
1/2: Renamed and Linked Stereo USB streaming.
3/4: Renamed and Linked Stereo USB streaming.
5: Renamed but not linked.
So, Channels 2 and 4 are being removed from the group because of the linking. I’ll have to test this tomorrow.