I can't autofill anything. From the Mac App a double click just opens a pop up that has the login.

Hi there @sbaker11

In 1Password 8, you'l need to click the Open & Fill button that appears on the website field, like this:

You're right that double-clicking an item will open it in a pop-up window. The same Open & Fill button will appear on the website field in that pop-up window.

Try that and let me know how it goes. :)

— Grey