I don't think there are any automatic notifications, but on the PowerSchool App's main page, there is a section called "Assignment Status" and it lists all of the missing, incomplete and late work for their child.
There is also a customization on PowerSource that will publish missing assignments in all portals. Download ID: 832
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This article on What can Parents see and do in a class? documents what Parents see and do in a class. This can be a great idea for enhancement if that doesn't meet your requirement.
We do have a new feature, the PowerSchool Ideas Portal, where users can submit their ideas directly to the Product team and it allows you to review the idea for status updates as well as share the idea with other users to support it by voting.
To learn more about the Ideas Portal, we recommend reviewing the article on PowerSchool Ideas Portal FAQs