Cart66 plugin – product insertion problem

I have installed the Cart66 Lite plugin on a WP multisite network. Specifically on https://biggshooter.com
It is running Genesis and the Landscape child theme.

Plugin appears to have set up ok but I cannot create product posts/pages.
The plugin documentation says to place cursor where you want it in the post and then click the Cart66 button on the toolbar.

when I click the Cart66 button, a small window opens, but it is blank, where there should be a listing of the products I have entered.

Any suggestions?