Putting this out here to say that I am also experiencing this, but also to let people know that changing the “Never Remember History” setting seems to allow signing in to Notes and syncing.
- In settings, trackers and third party cookies are always blocked. Always sending Do Not Track.
- In settings, Firefox will “use custom settings for history.” The 4 boxes below that are all unchecked except for “Clear history when Firefox closes.”
- In setting for clearing history, everything is checked. Notes still stays signed in when Firefox restarts
I hope Devs can fix this syncing error, but in the mean time I hope this helps people!