The site that I visit the most no longer appears in my "most visited" folder on my bookmarks toolbar It does appear in the "most visited" folder of my bookmarks library.
The drop down list that appears from the "Most Visited" tab on the Bookmarks Toolbar does not include the site that I go to the most. It was at the top of the list, and disappeared from the list two days ago.
Selecting the "Most Visited" tab within the "Bookmarks Toolbar" folder within the Bookmarks tab at the very top of the page also does not include the site I visit most.
However, when I go into my history, the site that I visit the most is at the top of the list that appears within the "Most Visited" folder. "Library" is the heading of this window.