I just bought an HX Effects. Super Excited.... Saw the note to make sure to update the firmware to 2.50. So I did immediately. I Was VERY upset when the updater kept crashing on Windows 7 or (on Windows10) would not find the device. Even got an RMA from Sweetwater to return it, after Line6 support came up empty, telling me that "It's not a normal problem we've seen." The techs at Sweetwater had seen it reported already but had no workaround.
Here's how to solve it.
Don't waste your time on 1) Driver installation 2) Updater download.
Download the entire HX Edit suite, which contains everything. That package registered the new drivers and Windows was able to recognize the device, update the firmware... and now I am in business.