PW5 Kindle jumps to the start of next chapter when opening a book

This is a very annoying issue that I have with my kindle.

FW: 5.14.0.1, jailbroken.

It will open the next chapter instead of where I stopped reading.

Is this the default behavior (I hope it isn't)?

What could be causing this?

All my books are azw3, converted from mobi / epub using Calibre.

This issue is present in every book.