Funky backing up action

I made an epub in Sigil, converted it to a mobi in Kindlegen and uploaded it to KDP.

In my Kindle (and a reader informed me of something similar) when I back up from the Egpigraph towards the cover, the Kindle will flip forward to Chapter 22 or Chapter 4. It doesn't do it every time but I'd say it does it 50% of the time.

Any thoughts? Thanks.

Some additional info. I do have an image on the title page. I wonder if that is somehow contributing to the problem.