range slider and local storage initialisation issue

I seem to be having a problem where by first visit to the page (presumably localstorage is empty at this point) and jplist shows "no results".
Interact with the slider and results appear.
Subsequent visits to the page (with localstorage now populated) and results show.

Any pointers for tracking this one down?

Site/page in question
http://www.themill-canton.co.uk/our-homes/availability/