There's a conflict with this mod and Maraxsis. Basically Maraxsis has it's own alterative recipe for the rocket, the way you select the rocket is not with a menu. Rather it's determined by location, which means Maraxsis overrides the menu for the launch pad with the default rocket part and removes the option to change the recipe.

Unfortunately, I cannot fix this on my end. Maraxsis manages this through runtime scripts and unless I also run a script every time a recipe gets set (which I don't want to do for performance reasons) I cannot do anything about this issue. If this mod gains a bit more popularity I will ask the maraxsis development team for support.

Thanks for the bugreport nevertheless! (´∀`)b

No worries, keep up the good work!