Zend certified PHP/Magento developer

Additional Data is not being imported into produces (full imports and focus additional data imports)

FIRSTLY I should note that all product data is importing correctly except the additional_attributes column.

I’ve been struggling for the past few hours with getting additional data imported into my products. I have succeeded in importing products into Magento however none of my custom additional data is being imported. I’ve looked on this forum and other places for guidance and tried a multitude of solutions including importing data with only the product sku and additional data however this hasn’t been successful.

The additional attributes work as intended, values can be inputted in the additional attributes under the product and the persist after a reload and are stored in the database. However when attempting to load the min from a CSV it is unsuccessful.

I’ve tried to export and import an existing product (deleting the exported product before importing) without making a single change to the CSV file but this is still failing to import the additional data.

Would appreciate any potential solutions or guidance to fix this issue as I have a CSV of over 1000 products that need to be imported and I don’t want to have to fill out the custom data for every single product.

Example data:

sku,additional_attributes
TN9BIXJY,JMP_CROWN_NUMBER=MB394

Upon reviewing both System.log and Debug.log there is no signs of any errors occurring during the import.