This extension is great, it is a must.
My bummer is that I was having
"privacy.firstparty.isolate = false" in firefox settings, for months, which prevented it from working.
I know this is not _your_ bug, but it would really be nice if the extension could check this config value and give a warning to user that nothing works!

The current result of the combination is a distastrous feeling of privacy.

Thanks for this great extension anyway!