I'm using the latest iOS and 1Password (details below) and following the autofill instructions from here: https://support.1password.com/ios-autofill/
I'm using 1Password only for autofill (i.e., no iCloud). With two different accounts (mine, which is 1P Families & a friend's 1P Personal) I'm seeing two different problems.
Issue 1 (w/ 1Password Families):
When I use iOS Safari and navigate to a login screen (Amazon in this case) I see the "for amazon.com -- 1Password • [email protected]" text above the keyboard as expected. Also the lock icon is right of this text (also above the keyboard). If I tap on the aforementioned text, 1Password populates the password field with an old password (one in the Password History). In contrast, if I use the key icon, tap on 1Password, use my fingerprint, and tap on the Amazon entry in 1Password, the proper password is entered. (Note: Above the 1Password... and below the Choose a saved password to use heading, I see two entries for Amazon. The top one houses the old password and unfortunately it seems to be the one that is being used by default. The second entry does include the correct password.)
To address this issue, I've tried the following steps (when each failed to correct the problem, I tried the next):
Even after these steps, 1Password is using the old password!
Issue 2 (w/ 1Password Personal)
Again I've followed the steps above to enable autofill. In this case, when I use iOS Safari and navigate to the Amazon site, I don't see any indication that autofill is available (i.e., no text or lock above the keyboard).
1Password Version: 7.6.2
Extension Version: Not Provided
OS Version: iOS 13.6
Sync Type: iCloud