I was just changing a login information for multiple sites (including Facebook) and unfortunately 1Password never recognised that the login has changed and did not ask me to update the login for the page. The only "non-standard" change I did is, that I actually didn't change the password, but I changed login (email).
When I tried to update password, everything worked well (tried on Facebook).
Can you please take a look on that?
1Password Version: 6.5
Extension Version: 126.96.36.199
OS Version: OSX 10.12.1
Sync Type: Not Provided