When a teacher or co-teacher assigns a piece written in or imported into Compose, other teachers will not be able to view this content when grading unless the creator shares their piece privately with their fellow teacher or publicly.
 

If you see the messages "Content permission required to view student submission" and "You do not have access to this content" (pictured below) while grading an assignment, contact your colleague and ask them to share their piece you with from within Compose or Content Manager.
 

For more information, see Sharing music with Compose and Content Manager.