Dear first of all, you need to know that the related products appear only on the single product page and you cannot select the related products manually because by default WooCommerce pick the related product based on the same tags, and categories.
Further, you cannot add the related product to any other page. If you are facing the issue of the column on other pages of your site then please share the page URL with us.
You are trying to set the related products column from the theme options. if you are facing the issue by using the theme option to set the columns on a single product page then please share the page URL with us and provide me the login access to your site in the below-listed format in the private content area and allow permission to debug your site which includes deactivating all the third-party plugins and on-site Customization as well so that I will check and assist you accordingly.
WP Admin URL:
WP Admin Username:
WP Admin Password:
Note: Please take the complete backup of your site first.
Regards 8Themes Team.
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