Currently when a teacher creates a new assignment (not using Calendar view) and the teacher sets the assigned date to a future date (that is not the current date), if the teacher tries to save the assignment an error is shows saying that the "Due date & time must fall after assigned date & time" which then causes the Assignment page to freeze and the teacher must exit out and start the Assignment creation again.
I was working with a support rep on this and we discovered that the system tries to put the current date (not assigned date) as the due date for the assignment, being due for the end of the day. This is why the error appears, and my suggestion being that whenever a future assignment is being created and there is a future assigned date, upon saving if there is no due date entered, the system should use the assigned date as the due date and set it to the end of the assigned day.
The only way this works without issue is if the assigned date IS the current date, which then the system by default sets the due date to the current date and there is no issue.