User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:73.0) Gecko/20100101 Firefox/73.0

Steps to reproduce:

I tried to clear all cookies and storage for a site. I restarted Firefox, and according to the Manage Cookies and Site Data window there is still 64.0 kB storage in use (see screenshot).
The site in casu is a Microsoft TFS site that does not work properly in my main Firefox window (it seems to time out on loading certain content). In Private Windows the site works correctly. This is why I want to delete all cookies and storage.

Hm, that site isn't loading at all for me and thus I can't reproduce the issue :|

Can you share a screencast of the issue and/or send me the affected profile (with the "unclearable" data) to the email address in my Bugzilla profile? Note that it may contain personal data and you don't have to share it if you don't feel comfortable doing so (though of course I intend to keep it confidential).

Thanks!

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is P3 (Backlog,) indicating it has been triaged, the bug's Severity is being updated to S3 (normal.)

Sorry, I only now see your response Johann. That site was probably only accessible when I was on a VPN. Iḿ not working on that project any more, and I also cannot reach the site any more. So this issue became non reproducible. Feel free to close this bug.