I sent 2 diagnostic reports when the progress bar flashed just now. The channel shows 100% signal quality and 75% signal strength.
I was also able to confirm that some level of pixelization was simultaneously occurring on the HDHomerun app while watching the same channel on my phone.
There is obviously some kind if interference even though the signal is generally very good.
It would not be so obvious when it happens if the progress bar flash can be disabled. Thanks for your help.