EDIT This is on my Win11 PC with everything updated...

This could occur if there are two folders with the same name. Here are two ways to investigate that:

For newly added bookmarks:

• Click the 3-bar menu button, then Bookmarks
• right-click the lost bookmark > Show in Folder

Firefox should open the Bookmarks Sidebar with the bookmark selected. You can scroll up to see where you are in the list, although if it's in a large folder, this can take a while.

For older or possibly duplicate bookmarks:

• Open the Library window using Ctrl+Shift+O ("O" as in Organizer) or on the Bookmarks menu > Manage Bookmarks
• Use the tiny search box at upper right to drill down to the misplaced bookmark(s)
• Right-click a bookmark > Show in Folder

Firefox should expand the folder list in the left column to show where that bookmark is saved.

Any luck so far?

Thank you for your reply, when I look at the folders in the side bar there are duplicate folders containing the same bookmarks, where they came from I have no idea, I also have no idea how to remove the duplicates! Is there a FF file with these in that I could find and delete them?

Like this:

The upper section has 'BT General Folder' the lower section does not have this folder.

Had a thought, I updated FF from a blue link on a FF. The link mentioned something about the Sidebar so I wonder if that has anything to do with it.

Years ago I looked at an add-on to help de-duplicate bookmarks. It would let you choose which to keep/delete, but it wasn't automatic. There might be other tools available by now that are more automatic, but I haven't kept up.

https://addons.mozilla.org/firefox/addon/bookmarks-organizer/

Two notes first:

(1) Sometimes, when you delete a bookmark, Sync quickly restores it. This is a difficult situation that others probably could offer advice on.

(2) You might consider running the database cleanup routine to make sure the file structure is healthy. Here's how:

Open Firefox's Troubleshooting Information page using any of these methods:

• "3-bar" menu button > Help > More Troubleshooting Information
• (menu bar) Help > More Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Near the bottom, there is a section titled Places Database -- that's the file which stores history and bookmarks. Click the button labeled Verify Integrity. There may be a 10-15 second delay before results appear.

If all is well, the report that appears below the button should start with:

> Task: checkIntegrity
+ The places.sqlite database is sane
+ The favicons.sqlite database is sane
> Task: invalidateCaches
+ The caches have been invalidated
> Task: checkCoherence
+ The database is coherent

Hopefully yours says that, so you can proceed with normal operations rather than thinking about rebuilding from a backup.

I have run the troubleshooting and the result is: Task: checkIntegrity + The places.sqlite database is sane + The favicons.sqlite database is sane > Task: checkCoherence + The database is coherent > Task: expire + Database cleaned up > Task: vacuum + Initial database size is 25600KiB

And a lot more information.

Progress! Thank you. I can now see the link I need in the lower sections folder, it even opens the file as it should. The link is still not shown in the same folder in the upper section. It looks like I need to remove (or rename just in case...) the folders in the upper section without affecting the lower section. Any suggestions?

It sound like you might want to move (or cut/paste) bookmarks from the unwanted same-named folder into your preferred folder and then delete the empty one. You should be able to drag the folders next to one another to reduce scrolling if they are in the same bucket (both in Bookmarks Toolbar, both in Bookmarks menu, etc.).

Okay, I think I get the idea. I haven't tried opening the same upper and lower folders from the search/manage folder option. Fingers crossed....

I have cut and pasted the contents from a few of the upper set of folders to the lower folders, then deleted the now empty folder. I do not have time this evening (UK Time20:07) so I will continue tomorrow. I then can go through each folder and hopefully sort by name so I should then see the duplicated files more easily and delete them. I will update this thread tomorrow and hope to be able to click the Solved link.