Outlook Desktop Notifications Not Working, But Enabled in Outlook and System Settings

[JackPiephoff]

User is on Windows 10 Enterprise. 

In Outlook > File > Options > Mail > Message Arrival, notifications and banners are turned on.

In System Settings > Notifications, notifs are on, Outlook is allowed, and banners are turned on.

Focus assist is off. 

Tried uninstalling and reinstalling to no avail. 

Weirdly, I wanted to check if a rule was causing this so I tried to get into the user's Rules and Alerts, but it won't open. That's when I tried the reinstall, and it still won't let us in that section...

Any thoughts?! 

[#2]

Wow, 6 months and no replies? I have the same issue with only two users in a terminal server environment (RDP from PCs to Windows Server 2016 using Outlook via M365). Although I've only tried a couple of your tweaks. I'll try all. Send any news on this topic if available.