I've got the same issue after upgrading to v4.8.1.0 on Synology. Sometimes I can see "Now Playing" for a second or less as the dashboard loads, but that's it. It's never fully appeared after the upgrade. In addition, the activity log doesn't show anything other than if I played a song through the web interface. Anything my wife or I play through Symfonium no longer appears. Neither of these were an issue in 4.7.