Unidentified Guest User appearing in download history for restricted file

Hi there – hoping you can help resolve this issue. One of the files we have set up in wp Download manager appears to have been downloaded by an unidentified guest user. The file permissions are set to only site members and administrators so unsure if this is a genuine aunauthorised download issue or a data tracking issue (i.e. that the file was actually downloaded by an authorised user and just not appropriately flagged / labelled in the history. I did notice that the Yoast SEO settings for this particular file had been left at the default settings which were allowing search engines to index and follow links so not sure if this could potentially have been related to the source of the issue but either way I have tested navigating to the direct file link in a non logged in browser and can confirm that I cannot gain access to the download. Need to try and get to the bottom of the issue asap to give client confidence that their files are secure. Hoping you can shed some light!