add to cart error

I have been using for plugin for a long time. I noticed my retargeting ads underperforming. My pixel is operating ok an all pages apart from add to cart and purchase. The pixel is 100% definitely linked to the products. The correct ID, price and information is showing on the product pages. But on the add to cart page I get this error:

WARNINGS
The contents parameter cannot be parsed properly. Please check the format of the custom data to ensure that quotes and/or array wrapper are present

Products Are Missing From Your Catalogs
Retargeting ads can’t run for 1 out of 1 product interactions on this page, because the products people have interacted with are missing from your catalogs.