Meybe these information could help to solve this problem?
Packing for Win (32&64) works great.
Copy my stuff to a new project even do not solve this problem.
Visual Studio is installed and runs.
I tryed Version 4.11 and 4.12 from the Epic Game Installer.
I did not had this Problem two Weeks before I installed the 4.12.
Best regards
BobKing23