I've got exactly the same issue! It has been driving me mildly crazy and I figured I was the only one who had this!
If I recall correctly, the "blank" network appeared after I tried to add an out-of-range network, then decided to delete it and start over. It was a normal network, no hidden SSID or anything. Everything seemed normal after I deleted the network -- but then after I successfully added another, I found I had the "blank" network as well.
If anyone figures out how to exorcise this ghost network, I'd appreciate it! I have no way of checking, but speculate that it may be slowing down the Eye-Fi card's connection process because it has to go through the step of checking a network that isn't there.