I have a theme that I modified in a test version of my site. In my test site the theme looks and functions exactly as it should, all the css, html, php run and displays with no issue at all. I was able to export the modified theme and moved it the live version of my site, but in there the css and html does not display as it should. The weirdest thing to me about it is that some elements have the custom css class that I added and others do not.
On my test site:
Custom classes being mocomRow, mocompFullWidthRow, mocompArticleThreeColumn.
On production:
Last two elements are missing the custom class but first three are not.
Are you using any cache plugin? If not, perhaps you didn’t properly transfer the template file that renders the post markup.