I have an eCommerce site, and have several products listed and all was OK, now suddently after I add the product, I cannot add that product to a product block. I click the select product, the list shows up, but when I click on the product I want, nothing happens.. If I click on an older product it is added. I had seen this once before and just re-created the product, but not even deleting and re-creating the product does not work. What did zI do wrong?

I did not create a product page.. but also did not do that for the dozen or so that I had previously entered.