Dear Jody Heald,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
We're sorry to hear that you're encountering repeated requests for Keychain access on your Mac, and that the "Lock Keychain Login" option remains greyed out under File menu in Keychain Access.
We've conducted a quick test on Mac and couldn't see the Keychain access request for SharePoint. However, we can reproduce the issue where the "Lock Keychain Login" option under the File menu is greyed out. A workaround we've found on lock is to right-click on the login in Keychain Access and select the “Lock after” checkbox, then enter 0 minutes.
For repeatedly Keychain access prompt for SharePoint, please try following suggestions we've found during search to check the outcome:
- Please click on "Always Allow" on the prompt to to check if it resolves the issue.
- Remove Keychain related to Office, OneDrive and Teams from Keychain Access to see if it helps.
- Force quit SharePoint in Activity Monitor/Activity Manager as it might be causing the pop-ups as shared in the similar thread: Microsoft Sharepoint keep pop up on my Macbook screen and require the - Microsoft Community
- Use a "clean startup" to determine if background programs are interfering. For more information, please refer to How to use a "clean startup" to determine whether background programs are interfering with Office for Mac - Microsoft Support
If the issue still persists after trying these steps, to help narrow down whether the issue is caused by a specific corrupted user profile, we'd recommend creating a new user profile on Mac to see if there could be any improvement.
We appreciate your kind patience and understanding that sometime the initial reply may not resolve the concern immediately or there may have some misunderstanding about your scenario, but we would like to hear the updates from your side and let's figure out the further suggestions.
Sorry for the inconvenience again and thank you for your precious time and cooperation. We hope that you are keeping safe and well!
Sincerely,
Rhoda | Microsoft Community Moderator