If I check the "Set this Product as 'New'" option on any product, only the first item in the Product Catalog displays the new tag. If I clear all the "Set this Product as 'New'" then the New tag is not displayed. Check the option again on any one of the products, and it appears on the first product (no others), no matter which product you have enabled it on.

This site was imported from v13, where it worked fine.