Structured data; Product

I have a price comparison site with 20k product, and on each product page I use the Product schema with the offers/AggregateOffer. For many of the products it works, and I can see the enhanced data in the google search results. The problem is that only around 200 out of the 20k products seems to be picked up in GSC. Even though all product pages are indexed, and there are no errors in the schema markup.

Does anyone know why so few products are being picked up?