So in the top row there is the sync icon...if you tap that it tells you what it is doing. On a successful sync, I see these messages: (I might have missed one)
- Starting sync
- Checking for updates
- Updating annotations
- Updating books
- Loading content
(I think I missed a message after updating books where it downloads books.)
It frequently gets stuck on the first two steps. If those don't complete in 30 seconds to a minute, they might not ever complete. After a while if it is still there, I cancel the sync, disable wifi, and wait for the sync to actually abort.
Then I re-enable wifi, wait for it to connect, and then retry the sync.
Sometimes I do that two or three times before I get a success.
Typically once it hits Updating annotations, it will eventually complete.
Updating books for me takes forever, but it doesn't seem to get stuck as often as the first two steps, so I usually let that run until the kobo falls asleep before I abort it and retry, but usually it takes less than 5 minutes.
Once updating books completes the book will show up under all books filtered with overdrive. If it fails to download the book after that, typically you can trigger a retry (after sync times out) by entering the My Books screen with wifi connected (which bypasses most of the steps above).
If you sideload the book with ADE and do the above steps, you might end up with two copies of the book on your device (one epub, one kepub).