Comment by rglover

Mentioned at the end, but Kobo's gel better with the KEPUB format. Calibre has a nice converter for this (I think it may be built-in now or still a plugin), but works great. Got a Kobo Clara Colour about ~2 years ago now and I couldn't highlight across pages until I bulk converted my library to KEPUBs. After that, you'd never know there was an issue. This post makes the whole mess make a lot more sense now.