It seems that highlights in Firefox are not working.
Maybe it's permissions fault. Even if I check tabs permission in extension options it then changes to unchecked and highlight can't be done.
There's "Additional permission required to use Highlights" information when clicking highlights in Raindrop via Bookmark Menu icon, but when I choose "continue' nothing happens.
PS. ALT+SHIFT+H shortcut isn't working too, it's History drop-down menu shortcut.