Media Key support - macOS?

Play / pause is working but next track / previous track are not.

They used to work, but stopped recently - I am supposing this is either OS version related or Audirvana version related, (or maybe linked to iTunes changes - but if that was so perhaps it is odd that play/pause continues to work). It would be good if the functionality could be restored somehow: if anyone has any ideas?

I’ve tried reinstalling Audirvana and restarting the computer etc.

I am using Audirvana 3.5.20 and macOS 10.14.6