I know there are issues going on but I don’t think this has been mentioned. I started a new category with subcategories a week or so ago. All of my products are appearing in the storefront. However, “no products found” in the backend. Glad its not the other way around 
Same issue for me.
New products are not moving in the categories on the backend only. They are showing correctly in the categories on the marketplace.
This was reported a few days ago, Zazzle is aware of the issue and they are working on a solution. https://community.zazzle.com/t5/technical-issues/category-question/m-p/52780#M5666
Looks like the issue has been fixed. My products are showing up in the correct categories, in the back-end and in my public shop. Thank you Zazzle for all your hard work.