When the coordinates (Lat/Lng) missing for a store, the address in the listing will turn red, as in the image below. Any store that doesn't have the coordinates available, will not appear on the map, so it is very important to have the right coordinates values for each of your stores.
Figure 1: Store with Missing Coordinates
To fetch the missing coordinates, click on the button "Update Coordinates" button, and then select a geocoder service from the drop-down menu before clicking on the "Import" button.
Figure 2: Store List - Fetch Missing Coordinates
If your API keys or access token is working fine, it will update the coordinates.