After importing orders, download permission is not granted

Hi,
I am trying to migrate my woocommerce orders for downloadable products and noticed that after importing the orders the appropriate download permissions for completed orders are not granted.
For my export settings I chose also under ‘Custom Fields’ _download_permissions_granted. I also can see on the exported csv-file that in the column _download_permissions_granted is all marked as ‘yes’.
Would be great, if someone could help me with this.