Can't select destination partition

[admin]

I found the problem. I had never seen a vhd before. When setting up win2usb, that is the default, and the default size is 14GB, which is exactly what I got. Legacy wouldn't boot, so I did it with a vhd but used all the available disk space. Works great now.

What was the problem and how did you solve it? I use VHDs all the time but cant get WTU to see the mounted VHDs. 

You don't need to create a VHD, WinToUSB will automatically create a VHD when creating VHD-based W2G drive.