I want to give @user feedback review in Teams Assigned PowerPoints

Hi @WHC 

Thank you for posting your question in the Microsoft Q&A forum.         

The message you’re seeing “We can't post this comment unless you share the file with all @mentioned users. Please share the file or remove @mentions first.” indicates that the file needs to be explicitly shared with anyone you mention in a comment. This is because @mentions trigger notifications and collaboration features that require direct access permissions in SharePoint or OneDrive. 

Previously, assignment-level access was sufficient for @mentions. Microsoft has updated this behavior to ensure that mentioned users have explicit permissions to the file. 

Here are some steps you can try to migrate this issue: 

1/ Open the file in SharePoint: 

• In Teams, go to the assignment file  
• Click “Open in SharePoint”. 

2/ Manage access: 

• Click “Manage Access”  
• Ensure the mentioned student has direct access. 
• If not, click “Share” and add their Microsoft 365 email. 

3/ Check permissions: 

• Use “Check Permissions” in SharePoint to confirm they have at least View or Edit rights. 

4/ Alternative: 

• If you cannot change permissions (due to school policy), remove @mentions and leave plain comments. 

For more details, you can refer to these Microsoft resources: 

• Use @mention in comments to tag someone for feedback 
• Collaborate with comments in Office 365 

Additionally, sometime the users in the same organization doesn’t mean they use the account in the same tenant. For example, they can use private email account. To better explain that, please refer to the figure below: 

In the Microsoft 365 admin center, you can more intuitively see that guest users are different from active users, and active users are what we call internal users. 

We can share documents with guest users through OneDrive, but the @ function is not available: 

Note: Please understand that our initial response does not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.  

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, please feel free to reach out.  

I'm looking forward to your reply.  

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