I removed the Indicator Panel in order to restore the dropbox icon per this suggestion, which also needed me to then restore pulseaudio to get its own icon. However the only thing in the Notification Area which is now shown is Skype; missing are network and Synology CloudStation (a NAS sync tool). Both are running at startup and working, hence me being able to post this message!
Does anyone know why the icons aren't showing up and how I could fix this?
Screenshot attached highlighting that nm-applet and cloudstation are running, and showing only the skype icon between sensors and pulseaudio panel items.