Hi,
Does it happen to many users in your environment?
We can try Ctrl + 6 to show all hidden folder and then check if it will appear right at the end on the Navigation Pane.
Besides, please check your connection status to see if the connection to the public folder is established. To do this, press Ctrl and right click the small icons of Outlook in the task bar. Click Connection Status.


Also, we can test whether the AutoDiscover is successful. Please press Ctrl and right click the small icons of Outlook in the task bar. Click Test Email AutoConfiguration. Select Use Autodiscover and then click Test. Check the result.

Please post back with any updates so that we can do more research.
Best Regards,
Perry
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