The issue is not with Store Locator Plus but with the Google algorithms. We have introduced work arounds to assist, specifically for those countries that Google seems to have problems with. Australia being one of them. (i.e some of the postal codes are not discrete enough for Google’s taste, there are other countries that use that postal code 2000 etc and Google will come back with the one that they decide is most relevant.)
The Experience add-on would help you (on sale at this time). You can test it out on the demo site. With Experience you can use “append” search (see documentation about this and discrete search ) the add-on also allows for additional filters and shortcodes . It also allows for autocomplte zip codes based on the locations in your dataset
I have a test site using Experience add-on and a page with Australia. I have shortcode center map at Australia since I have other map pages on my test site and I want that page to only show Australia. I then checked off Append search and added Australia. (See attached)
P.S Your site is not secure. Therefore Google will block some searches and will not allow Location sensor (GPS) to work. See this news article about the advantages of switching to HTTPS even if you do not need Location sensor
They consider this a security issue. You really should consider migrating your site to https and obtain a valid SSL. Google Chrome and other browsers are becoming very strict about this. The author has written articles about this . you may also wish to review the Google develop console, or research other articles in WordPress about the security. It is not necessarily an easy undertaking to migrate your site and it would require some extra steps. So use care and make sure you have a reliable back-up tool. ALWAYS
To show you what is being blocked on your site because of the http status, use your browser tools to inspect and look under the console box on your site , you will see these errors:
Error parsing header X-XSS-Protection: 1; mode=block; report=https://www.google.com/appserve/security-bugs/log/youtube: insecure reporting URL for secure page at character position 22. The default protections will be applied.
q2w3-fixed-widget.min.js?ver=5.0.4:1 q2w3_sidebar_options not found!
dEQoE7HmGQ4?rel=0&controls=0&wmode=opaque:1 Error parsing header X-XSS-Protection: 1; mode=block; report=https://www.google.com/appserve/security-bugs/log/youtube: insecure reporting URL for secure page at character position 22. The default protections will be applied.