There is a possibility that the one porduct you mentioned is corrupted in some way,  and though you are placing it in the correct location, the actual files inside the folders,  are not readable for some reason.

You can re download and try the updated files.

I had a look back up in your ealier post,  and you mentioned Runtime, Data, People,

The Runtime folder holds the Textures folder, which holds the Vendor's folder.

The Data folder is supposed to have a lowercase "d"  its a small thing but it can cause errors. There can literally be dozens of subfolders in there depending on the type of product.

And the People folder would have a subfolder specific for the generation of figure like Genesis 8 Female.

Store bought products tend to go through rigorous testing prior to release. Freebies may not.