Hello...I've been using Calibre since I got my first Kindle back in 2010.
I've just recently started having an issue when I sideload a book to any of the Kindles I have in my home... that the cover won't always show in the carousel, it will show the blue & white cover. I have searched all over the internet for an answer and here of course.
I have been able to make it work sometimes by choosing different covers, but never on a regular basis.
I've tried going from mobi>mobi or azw3>mobi, really any combination I could think of....
I'm feel like it might have something to do with the size of the covers or something in the metadata somewhere, but just can't figure it out and to be honest, I never had to worry about the cover before....I generally chose the cover with the highest resolution and it worked.
In the scheme of things, this isn't important, because my books are still easily readable as they are, but I like to try and figure out how things work and fix them if possible...that's why I have gone about 2 months before asking for help....I was hoping to figure it out....
Sorry for the long message, but figured the more information the better...thanks for any help given.