Here is a thread about the Vox's proprietary USB pinout that distinguishes it from standard Micro B connectors. If this eBay charger does not display proper charging information on the status bar, then you'll have to modify the cable.
I see that the Voxes currently being sold have a different, probably cheaper, charger than the originals, so they were likely sourced from a new supplier. I expect once the design went out for tenders, some manufacturers would have come up with their own chargers.