Issues with NAD C399 playing specific file types after activating Dirac via ROON app (ref#N05ODT)

Something similar was, at least, a known BlueOS issue:

There were lots of threads about it at one time:

https://community.roonlabs.com/search?context=topic&context_id=269155&q=88.2%20Nad&skip_context=true

I don’t know if Blusound fixed this in firmware updates since. Make sure your devices are updated