[Gaqs]

Hello everyone, I'm having a problem with some books missing covers when I send them from calibre to my kindle using koreader, most books are completely fine it's just like 3 books that have missing covers.

I'm not sure what's going on, the missing covers are all from series of books, they're all on the same format and all of the cover images have the same resolution as the other books of the series so I'm not sure why they would have the cover missing.

I tried removing the book and adding it again but for these specific entries it just seems like the cover won't show up.

Thanks in advance.

EDIT: Added an image of the problem in the attachments, as you can see the other books in the series show covers without a problem, it's just the 18th entry that has no cover. The cover shows up fine in calibre but not in koreader. I'm transferring books through wifi by using the calibre option in the koreader menu.