If I edit a Login and modify the password by using copy-paste, the strength shoots all the way down to minimum (a red dot on the left is all that is left); it will stay like this forever.
If I next re-edit, and simply delete say the last char of password, then put it back, the strength meter goes to sensible value. Except then when I Save the entry, it drops down to another, intermediate strength value. If then hit Edit again, it shoots up to what it was during last Edit. Save, and it drops down again.
1Password Version: 6.8.8
Extension Version: Not Provided
OS Version: OS X 10.11.6
Sync Type: Not Provided