The number of layers that a style reports refers to the number of images that the user needs to insert in that slide.
All the rest of the layers are considered as part of the slide style (masks, frames, backgrounds, decorations).
If all the three layers in the slide that you are showing, are non replaceable, it means that the user doesn't have to insert any image.
Therefore, Producer correctly shows 0 layers.
If you want your users to do anything in that slide - insert some pictures of their own, for example
- you must insert those images in the style too, and mark them as "replaceable".
In this way Producer will know that that slide style includes also some images, and not only things that are part of the style.
Hope this is clear, and that it helps.