Hi,
There’s not much I can tell you without seeing it, but here’s some things to try:
1. You should see any geocoding errors, but it’s worth trying with an unrestricted (no IP or referer restrictions) Google API key (or switch to Leaflet).
2. If you are using custom post types: check that your post types are checked in the ‘post types’ setting just above the geocoding, and make sure your post types are enabled for the “REST API”
3. Some field plugins will display the custom field title, not its slug. Double check the custom field names, or look in the database using a tool like phpMyAdmin (the table is wp_postmeta).
If that doesn’t help, feel free to use the contact form to email me directly to share screenshots or a login to the site.