When I double click a login item whilst in the Mac app (version 6.8.6) it used to open the url in the browser, fill in in the login and password and submit. Now it just opens the url and I have to click the browser extension button and click the selected site for it to fill and submit. This happens on my Microsoft Surface Pro as well.
1Password Version: 6.8.6
Extension Version: 188.8.131.52
OS Version: OSX 10.12.6
Sync Type: 1Password subscription