If the Magento listing doesn’t contain barcode information then on the next sync the product barcode would be deleted in Veeqo.

Veeqo will now only update your product barcodes if the Magento barcode field is not blank and has a barcode that is different to what you have stored in Veeqo.

For more information on how the Veeqo and Magento syncs work please check out This Guide