After a recent reload of one of the User PC. We found an issue on Adobe Reader DC where the “Save As” dialog opens but it displays a Blank Page. After a bit of research, we found this is not a new problem but has been an issue in other versions for a few years.

The Fix is fairly simple. Open Adobe Reader at the top Click Edit and then Preferences…
On the Preferences dialog choose the Category: General and on the right-hand side untick the option:
Show online Storage when Saving files

The Effect of this is Adobe will open directly into the Browse window where you can save into your required Directory.