Detect new usernames and passwords setting not working for Fastmail?

Ah ha! Great suggestion, the usernames are different. The original saved login had only the username portion of my email in the "username" field and it looks like Fastmail is expanding that to my full email when 1Password pastes it in. I didn't ever wait long enough to notice, you know, cmd-opt-\ and a return happens pretty quick.

Anyway, it's all good now, I'll be less averse to saving a new login for comparison next time. Thanks.