Why are @team_member_names not always appearing on drop-down to send notices on New Comment?

Question

I have an Excel spreadsheet stored in a MS Teams Channel folder that is used to communicate errors to the supervisors of those reps that make errors. At the end of each error record entered, the cell is 'right-clicked' and 'New Comment' is selected. Sometimes, when the @name of a known member of the Team is typed in, an error appears. Some errors say "We can't post this comment unless you share the file with all @metioned userss. Please share this file or remove @mentions first." Then a 'Grand Access' message appears which states "These recepients don't have access to this item. They will not be able to see or reply to your mention unless you give them access. - SHARE & NOTIFY (button)" It appears to work and send the notification, but not sure about that. Is there anything I need to do to assure it stops, or is it a normal glitch that resolves itself? Thanks.

Answer 1

Hi @Booth, Marcus,

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

I can get how disruptive it is when @mentions don’t behave consistently, especially when you rely on comment notifications to reach supervisors quickly.

First, could you please clarify a few things:

1/ Is the Excel file stored in a standard team channel or a private channel?

2/ Are all people you @mention members of the Team (and thus have access to the channel’s SharePoint folder), or are any guests/external users?

3/ Do you and the supervisors open the workbook in Excel for the web or Excel desktop?

If desktop, is AutoSave ON and the file shown as Saved to SharePoint/Teams?

4/ Does the warning appear only for some names or every time you @mention?

5/ Has anyone changed the library/folder/file permissions recently (e.g., unique permissions, or “Only members can view” changes)?

The warning appears because @mentions in modern Excel comments only work after the mentioned user has permission to the file. When Excel detects someone without access, it prompts you to Grant access or Share & notify so they can read the item and receive the notification. This is expected behavior when permissions aren’t already in place (especially for guests/external users added to Teams). In Microsoft 365, guests can collaborate when guest access is enabled and they are granted permissions in Teams/SharePoint.

While we're waiting for your answer to the above questions, here are a few steps you could try on time:

1/ Confirm Team/channel and SharePoint permissions:

• In Teams, open the Channel where the file lives > Files > click Open in SharePoint.
• In SharePoint, open the Document Library, locate the workbook > (…) > Manage access.
• Ensure Team members (and any supervisors you need to @mention) already have Edit or View access at the library/folder level before you add comments.

For private channels, only channel members have access, others will trigger the “Grant access” prompt until they’re added.

2/ Stabilize @mentions workflow:

• Prefer Excel for the web for commenting-heavy workflows: @mentions and notifications are most reliable when the file stays in the web experience with AutoSave.
• If using Excel desktop, verify the title bar shows Saved to <Team/SharePoint> and AutoSave = On. Save changes before adding comments.
• Use modern comments (the “New Comment” that supports @mentions), not legacy Notes.
• Avoid having the file Checked out or locked by coauthoring conflicts; check Version history if comments seem to “disappear.”

3/ Pre‑grant access (avoid the pop‑up):

• Add the supervisor group (or a security group/Distribution List synced to Entra ID) with Edit access at the folder level. Then @mentions won’t need ad‑hoc “Grant access.”
• If any supervisors are guests/external, confirm they’re added as Guests to the Team and that guest sharing is allowed by your tenant admin, guests can collaborate when configured correctly.

4/ Notification assurance:

• After commenting, use Manage access > Direct access to confirm the mentioned person is listed.
• Ask one supervisor to reply to the comment or confirm receipt; if they didn’t get a notification, have them open the file once (which refreshes their comment subscription) and check Teams/Email notifications.

If the “Grant access” / “Share & notify” prompt appears for users who don’t already have permission. Granting access resolves it for future mentions.

If the prompt appears even though the person is a Team member with existing access, or notifications don’t arrive after access is granted, this typically indicates unique (broken) permissions on the file/folder or private channel constraints.

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, please answer the questions above and 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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Answer 2

Hi @Booth, Marcus,

Thank you for clarifying those details, it really helps narrow down what’s happening.

Based on your description:

• The workbook is in a standard channel (not private), and all members have access.
• No guests or external users.
• The issue is intermittent and seems to resolve after clicking Share & notify.

This behavior is expected when Excel detects a potential permission mismatch, even if everyone technically has access. It can happen due to:

• File-level unique permissions (e.g., someone shared the file individually at some point).
• Sync delays between Teams and SharePoint permissions.
• Access context (opening via Teams vs. browser can trigger different checks).

Excel’s modern comments require the mentioned user to have explicit permission to the file. If the system can’t confirm that instantly, it shows the “Grant access” or “Share & notify” prompt. Clicking Share & notify ensures the user gets access and the notification.

Here are the steps you can try to minimize the problem:

1. Verify permissions at the library level:
   • In Teams, go to Files > Open in SharePoint.
   • Check the folder and file under Manage access.
   • Ensure permissions are inherited from the Team (no broken inheritance).
2. Avoid unique permissions:
   • If the file was ever shared individually, remove unique permissions so it inherits from the Team.
3. Use Excel for the web for commenting:
   • Notifications and @mentions are most reliable in the web experience.
4. Pre‑grant access for all supervisors:
   • If you have a group for supervisors, add it at the folder level so Excel doesn’t need to prompt.
5. Confirm AutoSave and coauthoring:
   • If using desktop, make sure AutoSave is ON and the file shows “Saved to SharePoint/Teams.”

Since the notifications seem to work after clicking Share & notify, this isn’t a glitch, it’s a safeguard to ensure permissions are correct. If the prompt appears even when permissions look fine, it’s usually due to sync latency and should stabilize over time.

I hope these steps help resolve the issue. Please give them a try and let me know how it goes. If the problem persists, we can work together to find another solution.

Thank you for your patience and understanding. If you have any questions or need more assistance, feel free to leave a comment on this post. I’m here to help.

Looking forward to your update.

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Answer 3

NOT AN ANSWER - I received an email stating that Killian-N answered the above question. However, there is not response to view. For some reason, it failed to post. Hopefully another try. If more info is needed, I'm working on Windows Enterprise office 365 working in a Sharepoint environment.