About the issue
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.