Running Channels on two different Nvidia Shield Android boxes. Cable is Spectrum digital through a pair of HD-DVR HDHomeRun CableCard boxes. if I'm watching live tv, after a while the video lags waay behind the audio and the frame rate drops more and more as time goes on. The buffer automatically increases, similar to if I had paused livetv, but the audio is usually current. The fix is to click right on the d-pad till everything catches up. This happens on both Shield boxes and is a daily occurrence.
One thing I noticed is that the drift starts when a local Spectrum commercial block comes on. I'm not sure what Spectrum is doing when they insert their commercials, but whatever it is, it makes Channels get confused, and the lag begins. If I leave live TV on all day the video can be hours behind the audio.