About the issue
On January 29, 2019, Google released Chrome 72, which has a new code signing certificate. Because of this change, 1Password 4 for Windows no longer works in Chrome 72 or later.
The last major update to 1Password 4 for Windows was in 2017 to allow it to continue working with modern browsers. It will only receive critical security updates in the future.
What you can do
To continue filling and saving in Chrome, you’ll need to upgrade to 1Password 7 for Windows.
If you don’t want to upgrade to 1Password 7 right now, you can still fill and save in other browsers, like Firefox, Opera, Brave, or Vivaldi.