Hi @Alex Hacker,
Thank you for posting your question in the Microsoft Q&A forum.
I would like to provide you with the following information:
To resolve this issue, please try the following steps:
1/ Clear the cache for Outlook Classic
Step 1: Completely close Outlook.
Step 2: Press Windows + R, then enter the following path: %localappdata%\Microsoft\Outlook
Step 3: Locate and delete the cache files (for example, OST files or cached data).
Step 4: Reopen Outlook and check whether the Calendar is displayed correctly.
2/ Create a new Outlook profile
Step 1: Open Control Panel > Mail.
Step 2: Select Show Profiles.
Step 3: Select Add > create a new Outlook profile.
After creating the profile, return to Show Profiles and select Always use this profile.
3/ Repair Outlook
Step 1: Press Windows + I.
Step 2: Select Apps > Installed apps.
Step 3: Locate Office 365.
Step 4: Select the … menu > Modify > Online Repair.
After completing the steps above, please share the Calendar again with the user and grant Edit permission to check whether the issue still occurs.
You may refer to the following documentation:
Fix Outlook Shared Calendar Not Showing After Accepting Invite - TechBloat
This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this.
Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.
I look forward to continuing the conversation.
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