I use a password manager with a plugin and have been running "Firefox Developer Edition" so I often update several times a week. I've been careful to watch the

I use a password manager with a plugin and have been running "Firefox Developer Edition" so I often update several times a week. I've been careful to watch the "Save Passwords and Logins" setting (which has generally been carried across updates) but if you change settings in about:config, it's definitely inconsistent as you've noted. Are you willing to share your custom settings? My changes to about:config were to enable U2F features before they were defaults.