Why can’t I see my whole class’s work in Google Classroom even though it shows up in Jotit?

If you can't see any of your students' work in Google Classroom for a single assignment, double check that when you created the assignment, you selected "Make a copy for each student" next to the PDF.

If you find that you forgot to select this while creating the assignment, but you don't want students to have to redo their work, here's a good work around:

Post another assignment (it doesn't need to have the attachment) and have students attach the page from the other assignment you created! They could also copy and paste into their notebook and then attach their notebook page. For more info on how students can do this, read How to Attach Pages to an Assignment - Google Classroom.