I've submitted my app four times, each time waiting a few hours for something to happen, then reducing the file size of my *.dmg and trying again. The first two seemed to have completed after 36 hours, but I no longer have that specific signed binary (and its a much smaller binary now anyway). The latest two are still "In Progress" and its almost been 48 hours.
I know my process isn't wrong, and my app isn't somehow incorrectly built or being denied because two were accepted. The outage page shows green for the notary tool (https://developer.apple.com/system-status/) so I'm not sure what the hold up is.