Don't know if it was an update for channels, or the latest tvOS update last week that did this. I use a HomePod and usually will select it as an audio source from the home screen, and then watch my recorded content from channels app. Before last week, it would work (although because of the slight delay, pausing or skipping commercials would cause video to stop while audio continued, and then pause video until audio caught up and then resume). Now, there is no audio that comes at all. I go to other apps and play video and it still plays through HomePod just fine, just not channels.