Pdf to epub book restarting halfway through

[Summerkins]

I'm trying to convert a series of novels from pdf to epub as my Sony reader does not like the pdfs.

The problem is when I convert these 4 novels there's a weird glitch with 2 of them, where it'll have the first 12-15 chapters, then will start from the beginning of the novel again and it will repeat this 20-30 times.

For example the first one went from chapter 1 to chapter 12, then would jump to chapter 29 (which wasn't actually chapter 29, but the acknowledgments) then go back to chapter one, and repeated this 23(ish) times before going chapter 1-28 and then jumping back to chapter 13 and repeating 13-28 23(ish) times before repeating chapter 29 (the actual chapter 29) 3 times.

I've tried converting it with and without Heuristic processing, and I am just really confused as to why this is happening.

I originally converted all 4 novels with heuristic processing, and had this problem, then tried it again without and it only fixed two of them.

It's really frustrating because I really want to read these novels, but jumping back between the chapters is just not working for me.

Any suggestions as to what I can do to fix this? There's nothing wrong (from what i can tell) with the pdfs, except that the font is kinda tiny, and the whole book is only 60something pages.

Any and all advice would be GREATLY appreciated.

Thanks
Dani