Outlook update to ver 4.2309.0 on IOS 16.3.1

Try a forced-restart of your iPad - as this will often clear an isolated software issue:

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)

Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

If the problem persists, the next logical step is to offload the offending App from the iPad - then restart the iPad prior to re-installing the App. Offloading preserves the App data - while completely removing the App from your iPad:

Settings > General > iPad Storage

Scroll down the list of Apps to find Outlook, then tap the entry; select Offload App.

Now restart your iPad as described above. After restart, reinstall Outlook from the App Store - and test.

You’ve now exhausted the likely fixes.

Being a recently updated Microsoft App, you would be best advised to seek assistance directly from Microsoft. They may be aware of the issue - and should be able to provide help, or a estimated time for a fix to be released.

The next step is to actually delete the App - which will remove both the App and associated data:

Delete apps on your iPhone, iPad, and iPod touch - Apple Support

After deleting the App, perform another forced-restart - and then reinstall the App.

Good result.

Clearly the previous Outlook update was the issue - now resolved with release of the most recent update.