I had audio problems on Directv Stream using the original Roku Streaming Stick+ Model #3810R. The remote failed on that Roku so I replaced it with the upgraded Roku Streaming Stick 4K #3820R and the audio issues have not recurred with the new Roku. I suggest an upgrade is in order if using the Ultra or model #3810R, both I understand have the audio problems. There was no audio issue when I used an old Roku Premiere (circa 2017) in the interim.
Doubling up on this post so more people may catch it. Sorry if improper forum etiquette.