Dear Grayson_27
Good day! Thank you for posting to Microsoft Community. We are happy to help you!
Based on your description, I have a general understanding of your problem, first of all, if you are using Outlook Desktop Client, please kindly try logging in to OWA (Outlook web app) with your account to check if you also cannot access shared calendars in Outlook on the web.
If everything is fine in OWA, please also kindly refer to the following
Microsoft have introduced a new option in the exchange account setting dialog: Turn on shared calendar improvements. Please kindly try the below steps:
- In Outlook, select File >Account Settings >Account Settings. You will see a list of your email accounts.
- Select the Microsoft Exchange account that you use to manage someone else's calendar and choose Change....
- Choose More Settings, followed by the Advanced tab.
- Select the checkbox next to: Turn on shared calendar improvements.
- Click on Apply then Ok
- Close and restart outlook
For Extra reference use this link": How to enable and disable the Outlook calendar sharing updates - Microsoft Support
If the issue still persists, please kindly provide us previous requested information (screenshot of the issue and outlook version with build details), so we can check and assist you further.
Thanks in advance for your understanding! Your patience and cooperation will be highly appreciated. Hope you all the best!
Sincerely,
Kerry Chen | Microsoft Community Moderator