Hi @Andy ,
May I know what environment you are using? online or on-premis?
How did the user access the file, can you describe it in detail?
It is recommended that you can do some troubleshooting:
First, Right-click the file and select Manage access-->advanced-->check permission to confirm that the user does have read permission.
Second,If there is no problem with checking the permission, it is recommended to remove all the permissions of the user, then delete the user account in the user information list, and give the permission again.
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