Android app not notifying me of new mail - missed bid for valuable contract.

As the title says. Little sore about missing that mail. I have ProtonMail android version 1.13.39. It's up to date according to the play store. Can't seem to find any tweeks on my phone to fix the notifications; keep alive, turn off battery saver, etc, that actually work.

Any help would be appreciated as the web app through FF mobile doesn't seem to notify very well either. Android version 10.

TIA