When I'm streaming Homicide Hunter (any episode, any season) with auto-play, the sound goes away whenever the stream moves to the next episode. The fix is to simply fast-forward a frame. Then the sound comes back until time to auto-play the next episode.
This only happens when I'm streaming Homicide Hunter on Hulu on an Ultra. I have three Ultras, and the identical problem happens on all. Earlier Roku models don't experience the issue, and the audio is fine on Fire TV, the native LG Hulu app, and the Windows Hulu client app.
Restarting the player or reinstalling the Hulu app have no effect on the problem.
This is a very peculiar behavior.
You didnt mention the model #(s) of your Ultras.
Regardless, you should report this to Hulu: