Firefox extension not automatically filling on macOS

Hello,

I am writing to you because whenever I use 1password mini with Firefox, the login are never auto-filled.

Note that I am using:

• macOS Sierra 10.12.6 (16G29)
• evergreen Firefox 55.0.3 (64-bit)
• 1Password version 6.8.1 (681006)
• 1Password extension version 4.6.10.90
• A running 1Password mini as indicated in the menu bar on top

I have set the preferences to be the following:

The steps I am taking in order to check that it (doesn't) work:

1. Go to a website on which I am not signed in (e.g. Hover)
2. I open 1Password mini with the keyboard shortcut (set to Alt + Cmd + \ for me), or with the extension button on the browser
3. My Hover login is displayed, but when I select it and hit Enter, or when I click it, the window disappears and nothing happens (the form remains empty)

Note that I also tried to use the Fill Login shortcut (set to Ctrl + Cmd + \ for me) on the website, and that the window appears only when I have multiple accounts, and does not appear when I have a single one, and when the window does appear, it has the same issue as above.

I can only login by opening the details, and copy-pasting the login and the password, which is very annoying.

1Password Version: 6.8.1 (681006)
Extension Version: 4.6.10.90
OS Version: macOS Sierra 10.12.6 (16G29)
Sync Type: Dropbox