Popup Display Rules broken (plus other errors)

I went to edit the Popup Display Rules and I can’t select any other pages than the home page (no pages appear in the options window). Also, none of the buttons (add, settings or delete) are working on any of the options. When the Edit Popup admin page loads, I’m seeing the following error in the console: Uncaught TypeError: jQuery(…).sgpbselect2 is not a function. I’m using the latest plugin and WP versions.