what the different between Manufacturer Part Number and Part Number - need help

I am writing to address a persistent issue I've encountered on my listing page: the inability to add an "Amazon Confirmed" identification. Through my interactions with myfitment, I understand that fitment data is linked to listings via the manufacturer part number. However, on my listing page, including the edit page and the template for creating new products, I am only able to add the part number and not the manufacturer part number.

I want to emphasize that these two numbers are not the same. For products similar to mine that have the Amazon Confirmed identification, their listing pages display the manufacturer part number. In contrast, my page only shows the part number. This discrepancy has made it impossible for me to link my fitment data with my listing.

I have attempted numerous solutions, such as opening cases for communication, uploading through templates, and creating new ASINs, but none of these methods have successfully displayed the manufacturer part number. This issue has been ongoing for two months now.

Please help me fix it.

I would greatly appreciate your assistance in resolving this matter.