I have been developing some themes for WordPress and I couldn’t understand why they wouldn’t appear in the preview when they were selected. I went through all of my code and tested removing parts that I thought might be the cause and no luck. Luckily enough I stumbled upon WP Contempo and found a solution.

They state that WordPress does not like spaces in their theme folders. So something like “magazine basic” won’t do it. But what I also noticed, was that “magazine-basic” won’t do it either. The only way to name a folder so that the WordPress preview works properly is to use the underscore. So something like “magazine_basic” works perfectly.