You should have a look into the app's FAQ-page:
https://www.aqua-mail.com/faq
There are some information about this Samsung specific issue with Android 8+ / 9+ (near the end of the list)
Thanks. but I read this, and many other posts on others suggestions to get it working.
In my case Aqua-mail was working fine before upgrade from Android 8, I was hoping if others had experienced the same and had suggestions to sort out the problem..
Have you tested what I wrote?
Paris Geek
I have tried everything you suggested, but to no avail.
I have found one interesting thing, that being if I go to widgets and move the widget icon to home screen, it will display the "Unread Message Count", which is fine.
However, this leads to another interesting thing, as I cannot get the widget icon, to locate in the Home Screen tray, so it will always be seen at the base of the screen, regardless of which of the home screen I am on, it simply refuses to be moved there, or be moved into a folder.
The Icon is square too.
Not ideal for me, but at least I can see the unread message count
All other widgets can be moved to Home Screen Tray or a folder