For those that have searched to this thread something you have to always do is make sure you have the battery charged and in your variax as well as an audio jack plugged in, otherwise the guitar will not use the battery and it WILL NOT use usb power.
Does not matter if you plug the audio jack into an amp, it just has to be fully inserted into the guitar.
Then the variax will talk over vdi-to-usb to your software.
I always forget the need to insert 1/4" cable and have a temporary panic :)