Hotmail/Outlook suddenly not sending notifications on iOS 12.3.1

I have my Outlook account linked to the iOS 'Mail' app. It's worked flawlessly for years. However, I noticed today that I am not receiving any screen notifications when I get an email. The phone will *ding* to signify that I've received an email, however I will not receive any notifications and nothing shows up in the 'Notification Center'. This is the first time this has ever happened to me in my years of iPhone use.

Under notification settings for my Hotmail account, I have Alerts turned on for 'Lock Screen', 'Notification Center', and 'Banners'. I also have the Banner Style set to 'Persistent'. These have been my settings for years; nothing has changed. Yet my phone will not alert me to new emails, except for a *ding*.

I've tried restarting my phone to no avail. Could this be a temporary issue with Outlook or Apple? I do still receive the emails without delay, but no matter how I fiddle with the notification settings, I cannot get the phone to notify phone me on the screen. Any help would be great, as this issue came out of nowhere. Thanks!