Sites recently upgraded to 3.4.3 with geocoding addresses in DB can't save contacts

Clicking on Save or cancel from the contact edit screen appears to do nothing. It turns out the cause is rather silly - hidden further down is

-122.167799

Latitude, Longitude
, Please enter no more than 10 characters.
Latitude and longitude may be automatically populated by enabling a Mapping Provider. (learn more...)

But, of course the user can't edit these fields & can't get past this

I think we should enable more things on Sandbox - e.g. geocoding & modules to make these things easier to pick up