I'm having no problem getting books filtered by Overdrive either by title or author. Could be an issue with your device or your library. Are you logged into your library on device?
This doesn't sound like your scenario, but if it was a specific book or two, it could be that it was a book (or version) that the library had but was not in the Kobo library. For on device borrowing Kobo uses it's own files so it's possible for a library to have a book that you could borrow via ADE and put on your KA1 but not be able to sign out via your device.
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