Originally Posted by LauraPony
This is normal. Kobo app isn't supposed to go to sleep when a book is open. This is to avoid something going to sleep while someone is in the middle of reading a page.
As for some of your other problems, did you check the date and time? If it is off, this can affect your bookmarks.
Hmmm this something else is wrong as I have had my Vox go to sleep before with a book open (I just hadn't turned a page in 15 minutes IIRC).
Date and time was one of the first things I checked when I started having issues with the library.