Unit in Course Freezes page — other units work

We are building three courses on this site.

Unit 6 of our Content marketing course will not finish loading in the admin menu. Other courses and units are able to edited. I deactivated all plugins except corsepressPro. I also emptied the cache and stopped minifying the js & css via Cloud-flair.

I have tested this on two computers and I am unable to edit this unit.

Please help.