I realize this is a really late reply but I was having the same problem and found this thread so if this, in turn, helps someone else in the future then good. Bodyslide has a left side and a right side. I don't understand how/why it works that way but I found that if you make your changes on one side, your character's body might be using the settings for the other side and so it just looks like the default body. What I did was use the little arrow button to copy all my settings from one side to the other then clicked the build button and it worked.