Hey Raf-
Thank you for the sample project. It appears that the virtual function that returns a null pointer is the cause. If you change the function signature so that a null pointer is not returned the project can then be packaged successfully. I have entered a report for the difference in behavior from other engine versions that you can find here: Unreal Engine Issues and Bug Tracker (UE-45171) . You can track the report’s status as the issue is reviewed by our development staff. Please be aware that this issue may not be prioritized or fixed soon.
Cheers