Support files in the Runtime folder

What influences whether a product has all 3 files in the support foler (dsa, dsx, and jpg/png)? I have many, many products that do not have the dsa and image file; which corresponds to products having missing preview images and scattered files in the lost and found.
Comments
Those are the metadata for the product, so only products with Daz-style metadata will have them.
Ok. What puts a product in the Daz-style category?
Examples:
I also do not understand why I have all 3 support files, but the preview image does not show up; as show with the attached images.
I do understand the file structures and location; and I have been adding preview images for products missing them. However, some of the situations don't make sense.
Older content has not been universally updated with metadata. The failure of some PNGs, apparently well formed, to show is odd but it does affect a scatterinmg of products.