Sorry for the troubles unlocking 1Password X. There was a bug introduced with Ubuntu 18.04's ibus package which causes password fields to not focus correctly in Firefox. The 1Password X popup (which is opened by hotkey or by clicking the 1Password logo in your toolbar) can't remain open without maintaining proper focus.
Fortunately, Ubuntu has fixed the underlying issue that was causing focus issues with the 1Password popup and many websites with password fields in Firefox.
You can learn more about the issue here: https://bugs.launchpad.net/ubuntu/+source/ibus/+bug/1765304
