I have noticed the same thing. I love this keyboard so I'd rather not replace it. I did notice that you can also get the keyboard to work again if you go into device manager and uninstall it. There are two instances of the device for some reason called "HID Keyboard Device". I uninstall both with the keyboard plugged in, disconnect from USB and reconnect to same USB, the keyboard autodetects and reinstalls again... then it works. It always shows two instances of the device though... I am sure that is causing a issue somehow. Can anyone help?
Actually, I just messed with it a little bit more and found you don't have to unplug and plug back in. Just uninstall both devices then right click on the category the device is under "Keyboards" and click "Scan for Hardware Changes". You may have to do this more than once but after doing that at least once or twice the keyboard detects again and auto installs then starts working again.