Setting the channel to none means "don't override the event channel numbers defined in the midi events".
I noticed after pasting in a riff from the Studio Instruments drum kit that the last note sounded like a piano instead of the symbol crash I expected.
Upon investigation I found that if I selected channel 10 for the track instead of none, it fixed the problem.
Sure enough, in the midi events for the track there was the last note and a few others randomly using channel 1 instead of 10.
Fixing the midi events to use channel 10 and resetting the track to prefer "none" kept the fix.
I suspect that when you open your project the TTS-1 gets loaded with factory presets then loads your preset to set up the patch/channel maps but doesn't load the sysx data needed to initialize any custom patch changes you made.
In the old days, what I did for every custom patch I made on my Korg M1 was to save the patch's sysx data and add it to my project and have the project automatically upload the sysx data to my M1 when the song loaded. This is likely what you have to do to overcome this for the TTS-1 - but I haven't tried it yet. I'm not even sure how I store sysx data for the TTS-1 patches.