OK - I'm now beyond frustrated. The app has worked flawlessly for months, but now I'm getting a black screen with a signal loss message every day and multiple times after watching for random amounts of time. There also seems to be random hiccups in playback too.
Here's the setup: AppleTV 4th Gen TvOS 14.2, wired connection, HDHomeRun Duo, Channels 4.3 (I did just update to 4.3.1 while typing this, but I don't see this issue addressed). The disconnection seems to be worse when more people are on the network (multiple computers), but I've isolated those devices to their own switch and have connected the router that connects to the AppleTV directly to the router from our ISP (I also have the HDHomeRun connected to the ISP router).
I've been chalking it up to the increased network traffic with the kids at home doing schooling, but here's where I'm sure it's with ChannelsTV - I connected our Samsung TV to the HDHomeRun using DNLA through the TV input menu and it worked flawlessly for over 4 hours. No signal loss, no hiccups, and the network traffic was the same or more than what we normally have.
As I said earlier, I did just update to 4.3.1 and will keep it playing, but this is not cool for an app that I paid so much for.