I have been reading a mobi book bought through and DLed from Amazon on both my Kindle Fire and Touch. The book is not modified or sideloaded, it is as stated above. Both the Fire and Touch had been doing a great job of whispersyncing farthest page read and bookmarks. Then about 60% through the book the Fire stopped whispersyncing. Yep, it is the Fire that won't whispersync because I DLed the book to my laptop and can tell the Touch is still whispersyncing properly but the Fire isn't. Even after restarting the Fire it won't whispersync this book anymore in either direction. This is really strange and frustrating. I've never encountered this issue before with a book purchased from Amazon.

I'm growing to dislike my Fire more every day, while growing to like my Touch more every day.