With nightly builds Windows can't format transmitter USB drive with default options, but it's possible to use "Quick Format" only. With v5.0.0 build format works with default options.
Why you want to format it? it is a virtual drive, delete everything and replace it with the new files. It probably does not implement all the hard drive functions like a normal microsd or such
With nightly builds Windows can't format transmitter USB drive with default options, but it's possible to use "Quick Format" only. With v5.0.0 build format works with default options.