Hi Leachie,
Does this issue happen to all users or specific user? Are you using Exchange account?
Are there any updates with this issue? If there are any error messages, please feel free to post back.
Besides, according to my research, we can also test the AutoDiscover feature of your account to see if it set correctly.
1. While Outlook is running, press and hold down the CTRL key, and then right-click the Outlook icon in the system tray or notification area on the lower-right corner of the screen.
2. From the menu, select Test E-mail AutoConfiguration.

3. Enter your email address and password.
4. Clear the Use Guessmart and Secure Guessmart Authentication check boxes.

5. Ensure that the Use Autodiscover check box is selected.
6. Click test.
Check the result tab to see if Autodiscover is detected.
Regards,
Perry
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