You don't have access to this file. Request Access - Attached file in MS Teams Chat for Returning User

A Staff user left our company, had their account removed, came back a couple of weeks later.

A new staff account was created, for the Returning User and access to relevant products, Teams groups, etc... set accordingly.

In MS Teams the Returning User was added back to the department Chat. Files are attached from other users in that department (from their OneDrives), but when the Returning User trys to open the document, it says: 'You don't have access to this file. Request Access', everyone else can access the files fine.

Requesting permisson, does nothing.

Permissions are set correclty on MS Teams, for the Returning User and everyone else in the Team.

One Drive and SharePoint settings for the individual users in the department look okay.

I previously had not used Teams to contact the returning user before, so if i create a chat and attach a file for the Returning User, they can open the file.

Removing them the system and re-adding them again, still brings up the error.

Any other new staff member, added to the department works fine.

I looked at the User ID Mismatch Diagnostic feature, using 2 of the current staff One Drive site Url's againt the Returning User, but it doesn't come up with any errors.

Any suggestions would be grateful ?