BLOG page changing when selected as post page

I am having issues with the Blog pages in High End. I have tried several different templates and they all keep doing the same thing. The page completely changes styling when I select it as the “posts page” under Appearance-> Customize-> Homepage settings.

If I leave the “posts page” blank my blog page will revert back to the page/style it is supposed to be (fullwidth masonry). I also noticed that the template option disappears when I try to make it my “post page”.

Should I just leave it blank??? Or is there some issue somewhere in the code?

The site is not live yet… i am still building it.