Fatal error: Uncaught Error: Call to undefined method

Hi See below error only on “one” category any ideas what might be causing this.

Fatal error: Uncaught Error: Call to undefined method WC_Product_Simple::get_available_variations() in /home/customer/www/*************/public_html/wp-content/plugins/schema-and-structured-data-for-wp/output/service.php:4130 Stack trace: #0 /home/customer/www/*************/public_html/wp-content/plugins/schema-and-structured-data-for-wp/output/service.php(4881): saswp_output_service->saswp_woocommerce_product_details(15) #1 /home/customer/*************/public_html/wp-content/plugins/schema-and-structured-data-for-wp/output/output.php(2389): saswp_output_service->saswp_schema_markup_generator(‘Product’) #2 /home/customer/www/*************/public_html/wp-content/plugins/schema-and-structured-data-for-wp/output/function.php(232): saswp_woocommerce_category_schema() #3 /home/customer/www/*************/public_html/wp-content/plugins/schema-and-structured-data-for-wp/output/function.php(128): saswp_get_all_schema_markup_output() #4 /home/customer/www/*************/ in?/home/customer/www/*************/public_html/wp-content/plugins/schema-and-structured-data-for-wp/output/service.php?on line?4130