When using SORT on a Numeric field, the numbers in Post Meta are stored as LONGTEXT so you need to cast them as numbers first.
CAST( product_page_weight.meta_value AS SIGNED ) DESC
When using SORT on a Numeric field, the numbers in Post Meta are stored as LONGTEXT so you need to cast them as numbers first.
CAST( product_page_weight.meta_value AS SIGNED ) DESC