Store Locator Plus has a checkbox under the General /User Interface tab called Force Load Javascript

Having this checked forces the JavaScript for Store Locator Plus to load in the header of EVERY page on your site. This can slow down your site and will disable various Store Locator Plus features. If you need to do this to make SLP work you should ask your theme author to add proper wp_footer() support to their code, or switch to a theme that behaves properly.

If you have this box checked , all kinds of crazy things can happen and Store Locator Plus settings may not work properly on your site. Even things that seem unrelated. For instance we have seen things such as when   “Force Load Javascript” is enabled your Results order will not work properly, even if you have the Experience  add-on. In most instances you should never check this box. The reason it is available is to compensate for poorly constructed WordPress themes and was intended for one customer as a work around.   It is a “work around” for people who are stuck with orphaned themes and it is not intended for general use. Consider changing to a WordPress theme.  Having this box checked can effect SLP add-ons, and functionality within SEO Pages (Power add-on), Location Sensor and other features.  When you first check the box off, a warning message will appear. Subsequently the message will not keep popping up.

Additionally, there are many themes and poorly constructed plug-ins that use old JavaScript or jquery ui that can cause Store Locator Plus to not work. SLP is updated frequently to ensure it works with the latest WP versions.

You can see common issues that effect many plug-ins under WP Support Forums or the FAQ.