I'm on Civi 5.20.0 and Drupal 7.67.
I installed and re-installed the Electoral extension, see
https://github.com/josephlacey/com.jlacey.electoral/issues/23
and
https://github.com/josephlacey/com.jlacey.electoral/issues/25.
To reinstall the Electoral extension, I deleted a number of custom fields, and option values, using the API, including City, County and State/Province from Option Group 21, Addressing Options.
I had used the Contact Summary Editor to create a custom layout. I have the Address block/pane on the top left of the leftmost column. Address is a 'predefined block', meaning it's in Core code, right?
But, now I don't see the City, County or State in the contact summary Address when editing, just when displayed. I do see Street Address, Postal Code and Country displayed and when editing.
The core.Address code is still there, I can see all the fields using the API Explorer to GET the Contact Summary layout, and I can update a record's Address values with the API Explorer. I just don't see the fields in the UI when selecting Edit in the Address pane.
UPDATE: I just upgraded to Civi 5.19.2 and still see the same error.
So my assumption is that I deleted something I should not have during the Electoral extension install and re-install process, like a reference to City, County and State in the Address pane Edit UI, but not sure now what, or how to restore it :) .
UPDATE 2: I was able to duplicate the problem on the dmaster demo site by disabling City, County and State/Province in Addressing Options in Option Groups, which caused those fields to not appear in Administer -> Localization -> Address Settings -> Address Editing
and so not in Address editing in the Summary screen for a Contact. And I was able to fix that on the dmaster demo site by re-enabling the fields in Addressing Options and selecting the checkboxes in Address Editing. However, the same fix does not work on my demo site.
UPDATE 3: I had deleted the City, County and State/Province option values in Addressing Options, duh on me, then added them back in, but of course, they had a new auto-incremented ID number. I thought that restoring to the previous, original OptionValue ID would fix the problem with the City, County and State/Province not appearing when editing an Address in the Summary screen. I was able to update the ID using mysql at the command line. But, changing the Option Value ID back didn't do the trick.