If your product schema is returning problems you’re likely to really have to get a bit more forensic to figure out why. Using the Custom Schema selection, you can create a custom Schema, fill from the Schema, and include it to the site. Or, you may make a blank Schema https://www.presta-addons-modules.com/en/opencart-seo-automatic-google-rich-snippets-json-ld-integration-opengraph-twitter-tags-schemaorg.html