@Sengchor @EmiElve I would like to tell that my listing is “Live” now.
It took a while, but the support team managed to fix it (however, shortly after, the listing got stuck in another bug. hahaha. However, everything was resolved in due time). I tried several times with the same support agent until he decided to manually update my products. After that, the problems were solved. I recommend that anyone who has similar problems contact the Fab support team.
For those who need a shortcut, it is here: https://support.fab.com/s/?ProductOrigin=FabSupport
(Remember that for the form to appear you need to be logged in to Epic Games. The page will reload automatically if you are already logged in with your account in the browser).