When you print from DWC the print jobs are uploaded to the internal SD card. So you're fine. The only time prints occur without the SD card is when they are sent from a gcode streamer over USB, like Octoprint, or direct connection to a PC with Simplify3D, for example.

Fixed in duetwebcontrol 2.0.1

I can take a stab at it when I come around to it. There’s a few other upgrades on my list before I return to this one, so it might be a few weeks. Could probably just fork it when the time comes and clean everything up - wouldn’t take too much more work for the full implementation as it would a mock-up.