So far, this problem is mostly on Firefox in the Mac, and on iPads.
Firefox on Mac: If PDF's are not opening in EBSCO or other databases, in the menu bar, try installing the Schubert-it PDF plugin, which is free for educational use. This is the plugin that EBSCO is currently recommending for the Mac.
iPad: Try the Puffin browser or another alternative browser. The default browser (Safari) may only show the first page of a PDF.
Additional PDF plugin issues are caused when the Adobe plugin (which doesn't work properly in some browsers) updates and resets to the default PDF reader. In Firefox, go to Tools and Add ons. Choose Plugins and disable the Adobe PDF plugin.
On Windows computers, older versions of Adobe Acrobat Reader may not display properly. Keep the Reader updated for performance and security reasons!