Safari favorites disappear when I reorganize them

A Few Thoughts:

Backup your Mac: To prevent data loss, be sure to Back up your Mac with Time Machine.

Then...

Boot the Mac in Safe Mode:

1. Boot into Safe Mode: Shut it down, wait 30 seconds, hold down the sift key upon boot
2. Use Safe Mode: Leave booted into it for 30 seconds
3. Boot Up Normally: When booting into Safe Mode items, such as login items, do not run, and things may be fixed, such as corrupt settings

Then...

• Clear Temporary Internet Files

Try clearing your Temporary Internet Files (Cookies & Cache) of Safari. Cookies perform remembrance of certain site-entered data. Whereas Cache keeps a snapshot of the last time you visited a site.  Use this Link: Clearing History and Cache - Apple Communities

Then...

• Scan for Malware:

Start with running a scan for malware, using Malwarebytes for Mac and remove what is found. Malware (short for: Malicious Software) is software that makes you Mac operate in undesired manors. So, once found, remove it from the quarantine.

Then...

• Reset your SMC and your NVRAM:

Sometimes changes are made to the system and then settings (i.e. for the Safari) become manipulated, technically. So, reset both on your Mac.

And, if Nothing Above Works...

• Reinstall the macOS:

Nothing would be lost. It's just that misplaced items would be placed back to where they should be and corrupt system files would be replaced by clean files. Go Here: Reinstall macOS - Apple Support. Use the third bulleted method: [command + r].

To prevent data loss, be sure to Back up your Mac with Time Machine, prior to the reinstall.

frantzmuller Said:

"Safari favorites disappear when I reorganize them: Thank you for your answer, I tried and I still get the error. So it's the MacOS install…but what can I do ? I reinstalled 10.15.5 (not efficient) then I updated to 10.15.6 (neither)."

-------

You are welcome.

Reinstall the macOS:

Nothing would be deleted. It's just that items that have become corrupted or deleted, would be replaced or reinstalled back to where they should be. Go Here: How to reinstall macOS from macOS Recovery - Apple Support

Important:

Create a Time Machine Backup First:

Prior to the reinstallation of your macOS, be certain to backup your Mac using a Time Machine Backup. That way, you can have something to restore your Mac from, should anything go wrong with the reinstall. Use an external hard drive that is at least 1.5 the total storage capacity.

frantzmuller Said:

"[...]So the guilty is probably the Radeon Pro Vega 48 8 Go driver, right ? Now the thing is… there is no update for this card on the AMD website, probably because this version only exists for the iMac. Does that mean I cannot do anything but waiting for Big Sur and hoping for a fix ?"

-------

Downgrade to Catalina:

There may be no fix for this, yet. So downgrade to Catalina. Did you create a Time Machine Backup of your Mac prior to this install? If so, login to Recovery Mode, and restore to it. Always be certain you create a Time Machine Backup prior to any upgrade whatsoever. And this is a pure example of why.

Elsewise, you need to do a clean install, and reinstall everything.

frantzmuller Said:

"Safari favorites disappear when I reorganize them"

-------

Trying a New Administrator User:

Create a temporary second Administrator user, log into it, and see if you still get this error.

• If you don't get the error, it is likely something configured in your current user.

• If you do get the error, it is likely to be the macOS install itself

Thanks for the video: https://youtu.be/bxpN8MOgFZ4

Viewing it, it looks as thought it is reorganizing the names to alphabetical-order after you maneuver them. Once automatically placed in its position, the name of the current tab (YouTube video) reappears.

So, it looks fine to me. 👍

Got that reply confused with another Post. Sorry