Contacts Map View - Many Customers Not Showing

I am using the desktop and mobile App. 

 

Only 23% of my Contacts are showing on Map view on the App. 100% of Leads are. 

 

I have 370 Contacts that all have postcodes but also State and "United Kingdom". Leads only have Postcode and sometimes State. When I convert the Lead to a Contact I fill in full address details. 

 

It has been suggested that by filling in the full address, this means that Google cannot always find it on their Map. And therefore I would manually need to modify the address (maybe remove "United Kingdom" or "Devon" (State) until Google recognises it / matches it. 

 

This is not practical to do for so many Contacts. 

 

Because we are an international company I need to identify Contacts by country, so I cannot just delete "United Kingdom" or State from a Contact, just so it shows up on the (Google) Map view.

 

Surely the workaround would be for Zendesk Sell to only ping the postcode to Google Maps. My Leads only have postcode and State filled in and this works 100%?

 

How do we achieve this? Because having these Map views when we are on the road is what made us buy the software.