Import Not Updating Listing When "Update Listing" is Selected – URGENT

Using Custom Post Type
Import is successful.
Import creates a new record instead of updating listing.
Option Selected: Update listing if post ID already exists.
Test file is exported, edited and imported. ID is kept the same. Import creates new record instead of updating.

URGENT request. We are dealing with mass record set and need to update without creating additional listings.

thank you!