I have put a ticket in on this but thought I would share with the community, fyi.
We are integrated with PowerTeacher Pro. Recently I changed the following Admin SIS Integration Setting to default to YES (by selecting it):
Default SIS Sync for assignments, quizzes, grade discussion
By having it set to "Yes," we are able to validate that all assignments have a due date (a requirement for grade passback to PowerTeacher Pro). Note that you must select the default SIS Sync to be "Yes" in order for the validation on due date to come up as an option.
By setting the default SIS sync to "Yes," we had two unexpected consequences.
1) If a teacher sets up a differentiated assignment and the default is set to "Post to SIS" (because it was set above, at the account level), then they are unable to save the assignment. This is good, in that grade passback is not supported for differentiated assignments. It's bad in that there is no error message and a teacher may not know why you cannot save the assignment. We have teachers who never post grades to PowerSchool and so do not pay attention to the "Post to SIS" option. An error message, similar to what you would get with no due date or an assignment name that is too long, would be extremely helpful here.
2) Courses that are copied and set to "remove dates" for assignments during the course copy do not have the due dates removed on any original assignment that had the "Post to SIS" set to "Yes."
If I get any answers on the ticket, I will let you know.