Upfront Builder messed up


I'm having issues with the Upfront Builder, mainly the Image Element. When attempting to add an image, the selection box is messed up, then when I click the + sign, the editor just gets fuzzy and freezes.

I've used Upfront on other websites, and I have a LAMP install with PHP 7.0, which makes me wonder if that is the issue, as I use PHP5 on the rest.

Any help or guidance would be appreciated, thank you!