When I connect my iOS 6 device for remote debugging for testing my mobile web application, The safari develop menu with my device name shows \"No Inspectable Applications\".
A few things to try:
On your iPhone/iPad, double-tap the Home button to bring up the list of running apps, close Safari (or appropriate Web App), then reopen
Quit/reopen Safari on the Mac
Unplug/plug back in iOS device
As a side note, I can attach to Safari with private browsing enabled on the iOS device.