No audio on some movies on Roku

[AlternateWitness]

Are you using a reverse proxy?  The dashboard not updating with the playback status would indicate some sort of web socket issue.  Not sure why that would cause issues with audio.

I am using a reverse proxy to access the server externally, but that is not what I'm doing with my Roku, I mostly use the server locally.
The dashboard does properly update with the video. Unless you mean it's saying something wrong when it says it's transcoding audio when there is none of it?