Rather than going to your test site, I went to two other bank sites where I have an account and changed my password there. It worked OK: 1Password suggested a password, I clicked on "use", it was filled into the New Password field and I was prompted to save it in 1Password. I saved the new password in 1Password and at the bank sites, then logged out and back in successfully with 1Password filling in my credentials.
Here is the URL for the site that is giving me problems: https://www.tangerine.ca/app/#/
