Issues with EPUB Text Resizing for Users

Hello all!

I created a Fixed Layout EPUB file that my organization is selling through Edition Guard and securely opens up Digital Editions. A big user experience issue we are running into is that nothing when users select the "aA" resize option on their desktops. Also, if users try the zoom control ("command"+"+") nothing happens either. Users ARE able to resize on touchscreen devices such as their phones and tablets.

Is there an export setting or user setting that will fix this?

Thank you in advance for your help!