First my versions (current versions of everything)...
Chrome Version 79.0.3945.88
Chrome 1P extension 188.8.131.52
1Password 7 Version 7.4.1 (70401002) 1Password Store
macOS Catalina 10.15.2
Problem i'm having for some months now, both pre and post-Catalina. I hit AutoFill blue button and the 1P extension window closes and the 1P-mini in the menu bar opens, showing full list of logins. If I repeat around 3 times, it'll fill the credentials into the site. So i've got used to this dance several times a day. Doesn't seem to be any particular site it happens on, can happen seemingly anywhere.
This little screen recording illustrates, as these things can easily be misunderstood ;-)
1Password Version: 7.4.1
Extension Version: 184.108.40.206
OS Version: OS X 10.15.2
Sync Type: 1Pass account