Gmail notifications stopped (Nokia 8)

Gmail notifications have always worked on my Nokia 8 until three days ago. It took me a day to figure it out, but the battery optimisation was doing it. How to fix?

Go to:
Settings > Apps and notifications > Special app-access > Battery Optimisation

In the drop down (I think default it says ‘Not optimised’) choose All Apps. Select Gmail and choose No optimisating.

This worked for me 😀

I was wrong. But I did find out what it was in the end;

Settings > Manage labels > Primair (check Labelalerts)
Settings > Manage labels > Social (check Labelalerts)
Settings > Manage labels > Promotions (check Labelalerts)
Settings > Manage labels > Updates(check Labelalerts)