Never mind, I found the issue!
I fixed the issue by looking at the Log when it attempts to rebuild the project.
The bottom line gave me the answer, I had to install Windows SDK v8.1 in order for it to successfully rebuild the project.
Link: Windows SDK archive - Windows app development
Just install this (make sure all the boxes are checked), Open the project, Click “Yes” when the error appears and it will build and open the project editor.
Hope this helped 