Update 12:24pm EST: The issue has been resolved.
We have been alerted by our users that the DraftKings CSV download is currently not working — when you click to download your entry history file, the DraftKings server is sending a file with no data. This occurs with a manual download as well as using the RotoTracker Sync browser extension. If you try uploading this empty file to RotoTracker is will (naturally) fail.
We have contacted DraftKings and will update the blog when we have more details. Hopefully just a temporary hitch!