We have many subsites, pages, document libraries on our main site. The "Team Visitors" permission on the site is set to "everyone except external users" allowing everyone in our company access to read literally everything. We have no issues on any of our subsites. We have a page that uses the pictures webparts and they have no issues viewing those photos.
However, on one page I have 2 file viewer webparts that I have uploaded a pdf to. None of our users, except for our admins, can see these files. They get the error "This item might not exist or is no longer available." There are no permissions on a page separate since it uses the site's permissions and there are also no separate permissions for a file or a webpart.
I have created 3 separate Microsoft cases and not one person in 8 days has been able to figure this out. This seems to be a very basic issue.
Every other pages, subsite, site, document library, file, folder has no issue. They can open the page just fine, see the headers on the page, even the file's description, just not the file itself.
I have even taken the pdf file and uploaded from various locations on my PC to ensure nothing is transferred from say OneDrive if I uploaded from there. It's a straight file upload from my PC.