User submitted posts plugin broken

Hi there, Following a recent upgrade of Clean Box, the rich text editor no longer appears in our User Submitted Posts (USP) plugin. I have tried de-activating all other plugins and that did not help. However, switching themes did help, so I gather it's a theme problem, but I like Clean Box and would like to keep using it. Page in question is here: https://north-shore.info/submit-post/ Expected behaviour is the bottom text box should show the full WP text editor, but instead there is nothing but the toggle for visual/text, which is broken. Thank you for any help