Why does my iCloud tabs on Mac OS X not work? I have a number of Apple devices (iPhone, iPad, Macbook and Mac Mini). I would like to use iCloud tab syncing between the devices, I have successfully enabled my macbook, iPhone and iPad but I'm unable to get it working on my Mac mini. 

I can confirm the settings are all switched on but the tabs are still not visible in Safari.
Anyone have any suggestions to fix this?

All devices are using the latest available software (iOS and Mac OSX)
Sign out and sign back into iCloud on your Mac. 

There was also a bug that if you had iCloud drive turned off for safari, your tabs wouldn't sync. So I would make sure that Safari is checked under iCloud Drive as well as iCloud settings.