Hi Etienne,
Thanks for the detailed information.
There’s a support article titled Unable to receive notifications on Work for Mobile on Android which may help.
Before I switched to iOS, I was using a Samsung phone running an older version of Android and had no issues with notifications on the app.
If this knowledge base article doesn’t resolve your issue, then maybe support provide a solution.
Let us know how it goes. Your findings could also help someone else out with the same trouble.