Within Assignments, you may see assigned content that was has already been completed, but still under the Assigned section rather than the Completed section. There are a few different contexts at play to understand the way the content switched between the assigned tab and completed tab once completed.
For example, if a user is assigned one piece of content and they complete it, the course will then be moved to Completed Assignments. However, if multiple pieces of content are assigned in one assignment, and one course out of an Assignment of three courses is completed, that completed content will not move to the Completed Assignment section until all content within the assignment is completed (in this case, the additional 2 courses assigned alongside the completed one).
You can also identify if your Assignment is part of a grouped assignment by locating check marks or dividing lines. As shown below, the check marks will indicate which courses are individually completed, and the dividers provide spacing to separate the groups of assignments:
In this example we see two assignments, each containing two pieces of content, and divided by a line to separate the assignments.
Assignment 1: Form and Continu Walkthrough, the Form Article has been viewed and completed, but not the Continu Walkthrough.
Assignment 2: Article For Spreadsheet and Freeformater Iorad Article. The Freeformater article has been completed.
If you are noticing an Overdue tag on content with a Green check mark, this is also noting the assignment is past the due date, even though the content itself has already been completed. If the Green check mark is present, this content is completed, and you can proceed to work on only content without the Green check mark.