SOLVED: Successful transcodes in browser, but not on other devices

[abaxi]

My CCwGTV 4K requests transcodes for my AV1 content.  But I explicitly use exoplayer (manually selected).  I see in the first log you posted that libVLC wanted to direct play.  I manually selected libVLC on mine and it ATTEMPTED to direct play (it did not go well).

What happens when you manually select exo as your preferred player?

Ah, I had LibVLC selected for troubleshooting this issue with Auto set before (also attempted direct play). Selecting ExoPlayer explicitly seemed to have resolved the issue, thank you!