I have this issue too, on a Theron I purchased a month or two ago.
I'm pretty shocked. I see this issue has been around a long time, at least a year and a half, and no definitive fix. I downloaded and installed the latest version available on your web site, and still it does not recognize that the device is plugged in.
Honestly, "please try another USB port" is also a really terrible answer. Please fix your software so I don't have to do wonky workarounds and hope it works.