Bug Report and Power-Bug Report Functions not working on Nexus 7 Android 4.3
I have discovered the solution (at least for my Nexus 7)! Here's what happens: 


Tap Take Bug Report
Take bug report "take a while" popup displays - Tap report
After about 30 seconds, the words "bug report captured" appear for about 2 seconds on left side of the top manu bar (the one with Time and Wi-Fi and other icons). 
An adroid icon then displays on the left side (where downloads and other status indicators display).
Swiping down on those icons displays an item "Bug report captured"
Tapping on the item brings up a "Complete action using" popup that includes Gmail.
Tapping the Gmail icon allow you to send the bug report text and its associated screen capture to yourself.


Pretty nice, but very easy to miss.