The API key is recommended, not required to make it work.
There are JS errors, which you can see in the browser console.
Timestamp: 03/05/2016 16:48:12
Error: Error: Syntax error, unrecognized expression: .main_menu .menu li > a[href*=#]
Source File: https://www.myfingerprints.ca/home/wp-includes/js/jquery/jquery.js?ver=1.12.3
Line: 2
This error is either caused by your theme, or another plugin using code that worked fine before WP 4.5, but now breaks.
WP 4.5 ships with a new jQuery version that doesn’t allow invalid code anymore, that used to work. This code in the error a[href*=#], should be a[href*=’#’] ( ” around the # ). The only way you can find out where it comes from is by switching back to your default theme and see if that fixes it, if it does, then you have to contact the theme author for a fix, if not, you have to try and disable all other plugins one by one untill you found the one that breaks it.
This is not an error caused by the store locator or WP itself, it’s code that should never been used in the first place, but just happened to work in older jQuery versions.