Kobo sync does not sync books which previously had no formats available.

[WeisseTeetasse]

Describe the bug/problem

When having a book with no formats in your calibre database, for example an unreleased book, a book you are waiting for a sale, synced from Goodreads tbr, a book you only own a physical copy etc etc and then add a format (only tested with epub) to it, calibre-web does not sync that newly available book to kobo.
kepubify triggers correctly, the .kepub is available on web, but not on kobo.

To Reproduce

Steps to reproduce the behavior:

1. Add a book entry with no formats to calibre
2. sync your kobo
3. add an epub to that book entry in calibre
4. sync your kobo again

Logfile

calibre-web.log.1:[2024-06-07 19:02:03,358] ERROR {cps.helper:187} Cannot find book entry 134
calibre-web.log.1:[2024-06-07 19:03:23,870] INFO {cps.tasks.convert:142} Book id 134 - target format of .kepub does not exist. Moving forward with convert.
Expected behavior

I would expect that a newly available book gets synced to my kobo

Environment (please complete the following information):

• OS: Debian 12/rpi/docker
• python 3.10.12
• Calibre-Web version: 0.6.21
• Docker container: [LinuxServer]:
• Special Hardware: [pi4]

Additional context

thanks for this software <3