Hi   !
This may be caused by an extension that isn't working properly.
Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

Does Firefox reload the favicon when you click such a bookmark?

Starting firefox in safe mode didn't help. I realize that none of the bookmarks on the Bookmarks Toolbar work, and they're all greyed out. However, when I got to "show your bookmarks (Ctrl+shift+B), most of those work, and most but not all refresh the favicon.

I created the bookmarks in the toolbar by dragging the URL to the toolbar. I also added folders to the toolbar and dragged urls to the folders. Was that the correct procedure?

"Was that the correct procedure?"

That has worked in the past and "we" have seen no complaints. Although, I "drag" from the Tab rather than from the Location bar, seems to "capture" the Favicon (website image) better; but I "drag" into Bookmarks Sidebar and don't even use the Bookmarks Tool Bar (horizontal space I have, vertical is more important for me with a wide-screen monitor).

First, is that a new customization for you? Or did that just crop up with the latest updates? Firefox 50.0.1 and then 50.0.2 within days of each other?

How many bookmarks do you have in those other folders? And folders within the folders on the BTB?

I wonder if there is a "limit" now?

You can also drag the tab on the combined star and "Show your bookmarks" button (either works) to open the drop-down list and drop the tab in the desired position.

Does this also happen with newly created bookmarks?

You can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

• https://addons.mozilla.org/firefox/addon/places-maintenance/

See also:

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file