WP-Property: Slideshow – Could not scale image

When we view a single property from a mobile device such as at https://www.ambergrisrealestate.com/properties-search/beachfront-starter-home/ it appears the Slideshow plugin isn’t working correctly.

We’re seeing the errors “Could not scale image”. Here’s a screenshot at https://www.dropbox.com/s/im27r5qw58i1a31/Screenshot%202017-11-07%2009.03.37.png?dl=0

Any suggestions on how to get this fixed?

The page I need help with: [log in to see the link]