Please could you follow the instructions on this page and let us know if it fixes it:
https://www.androidheadlines.com/2016/01/how-to-fix-missing-notifications-on-huawei-phones.html
Then, please test notifications on this page again:
https://www.beelivery.com/Driver/Diagnostic.aspx
If it works, try rebooting your phone and testing again just to make sure it actually works even when the app isn't running.
The app isn't working on my Huawei phone
