This has been reported for Ridex v1 and SFTP too. It's something to do with your PC and our server not disconnecting properly at the end of the page. (It's happened with every host/server we've had, not just our new one.)When I was downloading riides, occasionally it just refreshed the page instead of downloading the ride.
I can do nothing to fix this. All I can suggest is that you wait a few extra seconds when the page has appeared before selecting to download.