"no content available" via app.plex.tv from one device only

[JCHH]

This is strange I cannot get Plex using app.plex.tv on my Mac but everything else works just fine:

• On my Mac
  • I can access Plex via the Mac app
  • I can access Plex via <local_ip>: 32400
• Every other local device can access Plex using the app
• I can access Plex via app.plex.tv on my iPhone and iPad.
• All remote users (that sounds grand, there are only 2) have no problems via the app (AppleTV, Roku, iPad)

However, app.plex.tv on my Mac gives “no content available”.
I’ve logged out/in, restarted both Mac and server - no difference.

This is not a major issue, but can anyone help me troubleshoot?