Ctrl-Shift-Backspace stopped working

The keyboard shortcut Ctrl-Shift-Backspace no longer seems to bring me to
the last edit location.

The command works fine from the menu.
I tried resetting the shortcuts from ReSharper options.
I also verified the Shortcut in the Visual Studio Tools->Options->Keyboard
settings and it appears to be assigned.

We have noticed this problem on 2 machines.