[HarryT]

Originally Posted by BeccaPrice

Turns out my version is 4.0.1 - I'm updating the software now. There's nothing in the "What's New" description of 4.1 about azw3 files, but we'll see if this works anyway.

ETA: I updated to version 4.1, and another Mysterious Disappearing Book just appeared, so apparently that was the issue.

Thanks, All!

The whole point of the 4.1 firmware is to add KF8 support. Files with a ".AZW3" extension are KF8.