So I had something interesting happen over the last 24 hours, the m3u and the epg files showed up. There seems to have been a delay or maybe there is a persistent error that disappeared for some period of time. I'm not 100% sure. However, there still seems to be a problem because I am still seeing 0 channels in the m3u source that I set up. i tried completely deleting what I had done before, and adding it again and I can see that it spends a few seconds loading the m3u file, but after it's done, it just shows 0 channels.
So, I tried something different. I saw another post where someone mentioned just doing this directly on the Channels DVR pi using the custom build from Channels since docker is standard on it. That was super easy to do, however, I'm seeing the same thing there. No m3u file generated, no epg file generated and the same "undefined" error in the docker logs I noted above. So I'm going to wait a day and see if those files populate as well, which would be interesting to note. It would be great if the Channels team that built these could provide some feedback though.