If I open these in the built-in reader, and search, it will often show a list of search results. I select one, it opens a page without that result, and if I tap the arrow to go to the next result, it will say it has reached the end of the book.

Any idea what causes this?

Any fixes?

Any other reader apps which avoid this, without requiring swipes, or firing animation, etc.
Use KOReader
The built in reader on my Mars is useless for searches and also only good for PDFs/.