Found this one out by accident -
I had a program with an LP. I edited the template for the LP but forgot to approve the page in the program. I then cloned the program and previewed my new page and it wasn't correct. Took me a while to figure it out, but I had to force a change to either the LP or the template so that I could approve the LP which would then update template. In this example, I changed some of the CSS in the template and the cloned version wasn't showing the updated CSS.