Hello Juan,
We found that this brand is small and it would be easy to try and find the cause of this problem.
We found that by just changing the “Catalog Visibility” of the products from “Shop and Search” to “Hidden” and then changing it back to “Shop and Search” fixed the problem for the all 9 products.
I think doing this for 2k+ products would be impossible, do you now any other way for this?