You're probably seeing a recent change. Different channels (eg release vs nightly) recently started using separate profiles, because it was too easy to get data

You're probably seeing a recent change. Different channels (eg release vs nightly) recently started using separate profiles, because it was too easy to get data loss by switching between browser versions with the same profile. The storage files are backwards- compatible, but not forward compatible. I don't know if firefox clones your profile or creates a blank one when you switch channels, though.