Today we figured it out:
1. Put papers into scanner tray. Do not press any buttons on Panasonic device, ever.
2. Launch Multi-Function Station application on the computer.
3. In the application, click the little folder icon to the right of Scan. That will open the destination folder.
4. Click Scan in the application.
5. Click email in the application. (weird, huh?)
6. The machine will begin scanning all the pages. Shortly after it finishes, you will see your multi-page pdf in the destination folder.
7. Close / discard the email message that was created.
8. Drag your pdf to wherever it is needed.

You will not find this in the Help file or the manual. We spent so much time figuring this out, I hope that somebody finds it helpful. The same trick probably works on the KX-MB771, which has fax capabilities.