You are getting the below error message when saving an Assignment window in Console
Internal error: Failed to copy data object from input SDataObjectContext to output SDataContext
This can happen when you modify an existing assignment. For example, your Incident has been assigned to a Group and you want to assign it to a user, so you launch the existing assignment, select a user and save.
It is never recommended to modify an existing assignment. Always make sure that you can create a new assignment from the status of where the incident is currently at.
This will make sure that all notifications and response levels are working as should.
I would recommend to set your assignment window to be "Write Once". This way you wil force the analysts to always create a new assignment as they will not be able to modify the existing assignment after it has been saved. This will also make sure that you have an audit trail on the Incident letting know exactly what has happend when it comes to the assignment as well as having all notifications and response levels working as should.