[Solved] Early turn-in of assignment: No check mark!

My students are working on their first quest, and I have everything linked to Google Classroom. My first assignment was for them to write a paragraph in GC and to submit on GC. It was due at 3 PM yesterday for early turn-in (and hence extra points). Today, when I checked, a number of them turned it in prior to 3 PM, but there's no check mark in Classcraft indicating that. Can anyone help?