Kindle paperwhite has no cover thumbnails

I have a Kindle Paperwhite and I have a problem with thumbnail covers of my
work e-books.

1) book sent to @kindle.com after provide into the reader does not have a
thumbnail cover. Instead, there is a universal cover. It looks not elegant.

https://www.dropbox.com/s/62xcdyga2a...reenshot_1.png

2) the same book reader pre-loaded on the cable has the correct thumbnail
cover.

https://www.dropbox.com/s/wmvadyzm5s...reenshot_2.png

Does anyone of you know the solution to this problem?