I know from experience there can be audio problems with older Rokus and older TVs because some have HDMI limitations or the TV can't process Dolby Digital audio. While the Rokus will work with the more flexible audio formats in streaming services, they can't process what is in the TV signal delivere...

Did you -ever- have audio with that exact combination of HDHomerun, Roku and TV?

There are known problems with no audio with certain combinations of older Rokus and TVs. What make and year TV? Probably on a sticker on the set. A solution will depend on your answer.