Sequoia music problem

From a fresh boot, I can play any playlist but if I switch playlists, it will no longer play anything. It shows a random track playing but there is no audio. Restarting Music does not fix this, only a reboot does, albeit temporarily.

This behaviour started after the upgrade to Sequoia. A fresh install of Sequoia has made no difference.

Music media is stored on an external USB drive, as the library too large to fit on the iMac.

I'd be grateful of any help.