Feed is empty after download - how to fix that?
If the feed was created via the custom feed template in .xml, .txt, or .csv formats, it is required to manually add some product attributes to it because initially, the custom template does not contain any attributes.
For that, navigate to the Content tab and choose an attribute in the Attributes column. Then click the Insert button:
Yet it is possible to add some products here from conditions and generate the feed. As a result, it will be generated as an empty file because products here are not populated with attribute values.