I keep searching up "Breeder's Guidebook" and nothing pops up. And in the areas at the top and bottom where there's tabs to sort content by which section it's in, this mod isn't visible either. I know that the gender swap potion is also in this mod and that shows up, but I don't know anything else in this mod besides the guidebook, the horses, and the genderswap potion, so I can't test it on anything else.

I'm on 1.12.2, and I've got a lot of other mods.

Got the wrong book, haha! Anyways if anyone else seems to be having this issue, you don't need a guidebook, you need a regular vanilla book. Not a book and quill, just a book.