Please detail what kind of Galaxy you have and the last time you received a Tribute Notification.
Samsung Galaxy S9+
Haven’t received a tribute Notification in 8 days.
(For a week prior to it not working at all. Tributes were randomly being delayed. (So 14+ days of issues.) For a few hours it would be on time. And then for a few hours it would be 10-15 minutes late. Even with the device active the whole time. Meaning, not delayed because of sleep made.)
I have the S5 running 6.0.1
I am now receiving Tribute notifications, although I’ve not checked if they’re appearing hourly.
I’ll try to check this later today.
Ok, I’ve received three Tribute Notifications, all an hour apart, so it seems to be working fine for me.
I’ve also been getting notifications regularly this weekend. It did seem to be broken earlier but their fix seemed to work for me. I’m on an S8+.
The devs are gone for the weekend so I figured I’d try still some experiments with this bug. An hour ago I had a friend install the game and log into my account on her iPhone. And magically… The Notification showed up on my Samsung for the first time in a long time. She now uninstalled it so hopefully it continues to work on my end. 
I first played Gems of War on a Galaxy Note 4. I seemed to reliably receive notifications. I upgraded to a Galaxy Note 9 and haven’t been able to receive any notifications on it despite linking my device. The Note 4 still received them.
That could be due to new optimization settings that came with Oreo and Pie. Check if the device is putting GoW to sleep or not allowing it to run in the background.
I have a Samsung Galaxy Tab A, I only received 1 tribute alert yesterday and the game just happened to be running in the background when I received it. I usually close out the game.
I am receiving daily bonus alerts. I have not received a guild pet rescue, but that may be to no guildmates triggering one. Those are the only 3 I have selected.
I have not toggled alerts as suggested yet, I’ll try that now.
On a side note: I am not having notifications issues with any other apps.
This was also happening to me until today, but it’s apparently gone back to normal… hopefully it lasts!
Update: I received my tribute alert after disabling alerts, closing out game, then relaunching and reenabling alerts. Notification was right on time.
I’ll continue to monitor.