Custom field not available for feed

Hello, I am trying to use Woocommerce Product Feed Pro to create CSVs that I can use to create/update listings on other channels (like eBay, wish, and others).

Those channels often product data that WooCommerce does not, but I would like to store that needed data in Woocommerce products (invisible to users of my store), but exportable through the product feed.

Basically, I want to be able to create custom product data store in woocommerce, and exportable through the feed.

I tried to accomplish this using the WC Fields Factory plugin to create a custom field for a particular product. I chose an “admin field” because it does not need to be made visible to users.

The field was created in the product admin, like a charm, but product feed pro doesn’t see it, so I cannot access the value in the field in my feed creation.

I think a clue is this line from the WC Field Factory help, on accessing “admin fields”:

“Admin Product fields are stored as post meta ( here it’s product meta ), you can access any admin fields just like accessing any WordPress post meta. using get_post_meta() function.”

So, any suggestions on the broader question of how I can add custom fields to products and then export them using the product feed pro tool?

Thanks