I added that to my .htaccess and it fixed most of my issues. I have multiple levels of authentication on my files. That fixed it for the lowest level security, but not the upper levels.
Basically I made it so that registered users can’t see anything until I put them in a custom role I created. Then there are more files that only editors can access.
Subscribers no longer have access to PDFs like they did before the .htaccess mod, but members in the custom role have access to the editors PDFs.
This isn’t that big of an issue because at that point I’ve already manually moved them to the custom role, but obviously not ideal. It works perfectly for jpgs and pngs, but the PDF files no.