This likely means your link has been disabled because it does not meet the security requirements set by the Content Safeguard policy. If the link has been restricted under an access control policy, the following message will be displayed upon link access: “Access to the file has been restricted by the Administrator.” Due to this feature being in Beta, we highly recommend that you investigate inaccessible links via the Web UI.

Learn how to test link access here. To fix inaccessible links, you'll need to follow the steps in this article