ACF field showing

Hi there,
I had already mapped an ACF Custom Text field, and it worked fine.
But I have now created another ACF text field and it is displaying on the XML feed as something like: field_5ec1197a96f0f

This appears to be what was reported here:
https://www.ads-software.com/support/topic/acf-and-product-feed-pro-for-woocommerce/
and here:
https://www.ads-software.com/support/topic/acf-and-product-feed-pro/

Also, even though this custom field has a data entry on every product, only one product is pulling through that field on its mapping.

Since others have already reported this issue of the field showing odd data, it would seem there may be some kind of incompatibility with ACF.

Any suggestions?

Thank you.