How to check why some pages are not scraped?

https://www.heran.com.tw/product-category/%e8%ae%8a%e9%a0%bb%e5%86%b0%e7%ae%b1/ I want to scrap all the products in this page and used xpath: //*[contains(@class,'has-post-thumbnail shipping-taxable product-type-simple')]  It works well but some pages are not scraped. Like HRE-B5825V 0rHRE-C5721V that I can't find why the automation can't scrap these pages. (no info from log as well) Could please tell me how to check this issue and how to fix it? Thanks, Luke