For those using this feature for a long enough time, have you seen misfiring or emails that disappear, you couldn't retrieve ? When using keychain as a passwor

For those using this feature for a long enough time, have you seen misfiring or emails that disappear, you couldn't retrieve ? When using keychain as a password manager, once in a while when creating a password for a new site, it would generate it and complete the account registration, without properly saving the generated password. I'd hunt for the site item through keychain's list and not find it, and go through the "Reset My Password" for the site, except if time passed I might not even remember which email I used to register. It was annoying enough for passwords, but not critical. For emails there's probably situations where the account is just lost and the only option is to create a fresh new one. How good is their implementation for this ?