Digital Editions says that books are loaded on Kobo, but Kobo's library is empty.

Hello, I am having trouble loading content onto my Kobo (Aura H2O). I previously was able to add library books with no trouble by following the directions online, but it has spontaneously stopped working.

Situation:

I have books loaded onto Adobe Digital Editions on my computer, and an authorized device (Kobo).

I add the copy the book to the device.

When I click "Kobo eReader" within Digital Editions, it says that the books are loaded.

I eject the eReader.

There are no books in the library.

I have already tried:

Reinstalling Digital Editions.

Re-authorizing the device

Factory Reset button on the device.

I called the Kobo customer support line, and they referred me to Adobe.

Any ideas?

Thanks for your help.

--Lisa