I was doing the exact thing you had mentioned to do but for some reason it was breaking my frontend. I am pleased to let you know, I figured out what I WAS DOING WRONG.
Turns out, I had both the premium and the free version in my Documents folder. I mistakenly copied over a few of the files from the free theme by mistake, rather than copying over the files from the premium theme.
Even I make mistakes. Thanks for your guidance. You are appreciated.