Without your Plugin environment nor your url (see Posting Guidelines) can only guess which of these two relate to your issue, or if it does since I have no info to go on.
Below fixed in SLP 4.6.2
if you Are:
1) running WordPress version lower than 4.4.
(you should really be upgrading WordPress to something newer than 4.3 due to a number of security patches introduced in 4.4, 4.5, and 4.6.)
if you are you using Multisite
2) WordPress changed version 4.6 to deprecate wp_get_sites() which returned an array.
They now require get_sites() which returns an object.
Thanks to these changes in WordPress, Store Locator Plus now needs to carry around a lot of extra code to basically say “If you are on Multisite and are using WP 4.6 do this… if you are on on Multisite and less than WP 4.6 do that… and if you are NOT on multisite do something completely different”.
As an aside, most of the multi-site support options are built into the Premier Plugin for Premier Subscription users. If you are running multisite you really should be enrolled in our Premier program.
If neither of those apply to you, please provide your Plugin Environment , as requested in the Posting guidelines screenshots is better than typing it in , there are other things that could effect your site (php versions) etc.