XD Project won't sync up with a co worker in the same project.

A co worker and I have been working in the same XD projects for days now and then all of a sudden none our projects will sync up when we are collaberating. I've tried inviting him to a new project and he can join but he cannot see any work that I add to the project. It has an icon that signifies he is in the project but when I click on his name it says "This person is not interacting with this document". We have tried logging out, restarting, and we are just not sure how to fix this.