What happened to Notification Sync?

[TheMan876]

Google talked about syncing notifications at IO. You swipe away on your phone and it won't be there on the tablet. I think that was KitKat but here I am with a nexus 9 full of notifications that I swiped away from my 6 during the day.

 

[zorak950]

Notification sync requires app support. If the developer doesn't use the necessary code, there is no syncing.

 

[TheMan876]

I don't think there are any apps using it... I even have google apps with notifactions on both.