Why doesn't Kindle 8 show some things in books?

Question

Amazon Kindle

I bought a new Amazon Kindle 8 3 days ago. I dropped a few books through Colibre and noticed that the books are not read correctly. For example, in Kantor's book, Javascript(pdf) does not show code examples or some pictures that are normally displayed on a computer or the sequence of text is not correct.
And in the book, Einstein Walks on the Moon (mobi) does not show the diagrams and pictures that are in the book, and in general I noticed this in many books. Book formats are mostly mobi but there are also a couple of pdf.