When going to one specific record, we are getting the message "Warning! The File Explorer needs to be synchronised with the list of files associated to this record. Click to synchronise." We synchronise, the files do appear but the message never goes away. What causes this?

When going to one specific record, we are getting the message "Warning! The File Explorer needs to be synchronised with the list of files associated to this record. Click to synchronise." We synchronise, the files do appear but the message never goes away. What causes this?