Whilst prior to upgrading the Safari browser may occasionally fail to find the location, since upgrading to macOS Sierra, the websites that use location features built into the Safari browser, now fail all the time. This includes when using Safari and Opera. Chrome only supports sites which use SSL, so I tend not to use Chrome for much on the MacBook Air. The sites all work fine on mobile devices including iOS and Android.
Applications such as Google maps and Apple maps have are OK with finding the location, so the problem appears to be more related to location services used by the browsers such Safari and Opera. It is a design of the Chrome browser not to support websites that don't use https, so Google Chrome can't be tested for sites using http.
An example that will enable you to test if location services are working is my site www.PetrolPricesMelbourne.com.au.
I've since read that Safari on macOS now requires sites to use SSL if they use location services.