Huh? I don't see any Full Disk Access in the Privacy window?
At the top of the window I have "Enable Location Services" and the box is already checked but the entire line is greyed out.
Below this line I have "allow the apps and services below to determine your location"
Dragging the .pdf out of the e-mail and on to the Desktop does allow for the opening of the file but just out of academic interest, I'll pursue the lead that you have given me which should result in me being able to open the .pdf just by clicking on it while it's still in the e-mail. So then, once again, how do I add Full Disk Access?