Problem with Ameli.fr

I already had an Ameli Account before using 1password. I didn't remember the password, so I used the "reset password" link,
I used 1password to fill the reset password fields, so 1password saved the new password.

Then, I disconnected and tried to connect using 1password. It didn't work. I filled the fields manually, connected, and 1password didn't prompt me to save anything. I re-disconnected and retried, it still didn't work. So I wend into 1password, manually added my username there (it didn't get it at the beginning because the reset password page don't have any field with the username), and tried again.
This time, 1password suggests me to register with my account name. I want to login, not to register, so I clicked on the 3 dots and chose "credentials" instead (I'm note sure about the English name, it's the one with the lock icon), and chose my Ameli account. It correctly filled my username, but it also filled the password field with my username. I tried to fix it by pasting my password in it and connecting, still no popup asking me if I want to update my credentials in 1password. And after disconnecting / reconnecting, I still have the behavior above.

When I look at my Ameli credentials in 1password, I have my username in the username field and my password in the password field. If I open the details of the web form, "code_personnel_portlet_2nouveauCode" contains my password and "username" contains my username (in this order). If I open the Firefox developper tools on the Ameli login page, the login field has the id "connexioncompte_2nir_as", and the password field has the id "connexioncompte_2connexion_code". I guess "code_personnel_portlet_2nouveauCode" comes from the reset password page ("nouveauCode" means "newCode"). I think I could fix my problem if I could edit these fields, but I didn't find how.

I guess I can fix it by removing my Ameli account from 1password and re-adding it, but I would prefer if 1password could be enhanced to work around cases like this. I don't think my grandma could have fixed it herself.

1Password Version: Not Provided
Extension Version: 1Password X for Firefox version 1.14.3
OS Version: Windows 10 Professional, version 1809
Sync Type: Not Provided