Occasionally songs are removed from a catalog by a label. Those songs are not playable and greyed out, if you added them to the list earlier. Volumio does not handle this properly in the “My Traks” list of Qobuz. See the “Maria Phil” song in Qobuz below
compared to Volumio.
At the same time, if you start a song further down in the list, Volumio always skips to next track. To play the track you want, you always have to start with the previous song (-1).
When I correctly recall I saw the same in a tracklist from Tidal during buster period.