In the meantime, I will explain the error message you got. That message is what happens when you try to send notes from tracks...with midi channels that overlap with the ranges of other channels that are channelizing.
For example, let's say you have a source track on midi channel 1 and a source track on midi channel 2. and then on channel 1 you have a note with articulation ID 2. Channelizer will detect that as an error, because it is. You would need your source tracks to be channel 1 and channel 3 to avoid that problem.
from the sounds of your explanation I think the problem is that you are doing something with your articulation set or the source channels that does not make sense with channelizer. Do not assign any midi channels in the articulation Set. Let channelizer do that. and your source channels need to stay out of each other's way.
So for example, if you have a source track on channel 1, with art's 1-3. That means that will use up channels 1-3 in Play. You should not have any other source tracks using channels 2-3, the next track should start at channel 4...otherwise you will get the error message you mentioned with channel overlap.
OSX 10.15 (Catalina) on OpenCore - Logic Pro 10.6.2, VePro7, Mainstage3
5,1 MacPro 3.46ghz x 12 128gb ram