Is that folder located in the Unsorted Bookmarks folder or in the all Bookmarks folder?

Good point. It appears that my original post was wrong, due to my general ignorance about Firefox. When I clicked on "organize bookmarks," the new folder clearly is not under unorganized bookmarks.

The situation is that under the "bookmarks menu" there are several folders, then several boommarks that are not in folders. The bookmark folder that I added after the upgrade follows the bookmarkes that are not in folders.

In the past when I added new bookmark folders, they would be added before the bookmarks that are not in folders.

What I fear is that this new bookmark is somehow partitioned from the existing folders since it doesn't "sort by name" with the remaining folders.

There are several bookmarks in the "unsorted bookmarks" file.

If somebody doesn't have an explanation, my next step is to either delete or put in folders all of the bookmarks that are not in folders in the "bookmarks menu" file. When completed, the new folder should be adjacent to the existing folders. If it still doesn't sort, it clearly somehow is segregated from the folders established before the upgrade.

I've never had this problem in the past with prior upgrades.

Thanks for your assistance.

I "cut" the new folder and pasted it after the existing folders. Still, when I click on "sort by name," this new folder established after the upgrade, does not sort.

I noticed in the organize menu there is something called "new separator." Searching in the help menu, I couldn't find anything when I searched for "separator" or "bookmarks separator." I wonder if somehow the new folder is separated from the old folders and, if so, how do I combine them.

I worry that when I add new folders in the future that I'll have this same problem.

Firefox sorts bookmarks and folders between separators, so if there are any separators then that can cause it.

It is still not clear to me where the problematic folder(s) in located.

Is that folder a sub folder if the Bookmarks Menu folder?

There should only be three major folders (Bookmarks Toolbar, Bookmarks Menu , and Unsorted Bookmarks) in the All Bookmarks folder. If there are more then there is a problem with a corrupted places.sqlite database file.
If that folder is located in the Bookmarks Menu folder then Firefox will sort that folder (but not its contents) if you choose "Sort By Name" for the Bookmarks Menu folder.

See also http://kb.mozillazine.org/Sorting_and_rearranging_bookmarks_-_Firefox

SortPlaces: https://addons.mozilla.org/firefox/addon/9275