Google Classroom assigned document is not accessible by teacher or student
The problem
Occasionally a Google classroom file may become corrupted with neither the teacher or student able to open the file.
Identifying the problem
A student sees an assigned document as "Drive File Unknown File" as shown in the below screenshot.
Resolving the problem
Have the student follow these steps to resolve this issue:
1) Click the X to delete the file
2) Click "Make a copy"
The file should then be recreated and available to the student and teacher to access.