Authentication dialog not working from gnome-shell search

This bug is significant and repeatable.

My system is up to date Ubuntu 12.10 x86_64 running gnome-shell (3.6.2-0ubuntu0.2) and using gnome 3 team ppa. As of recently(?), whenever I try to run any program that requires authentication, e.g. synaptic, then I press the meta key, type e.g. "syn<enter>" and the shell authentication dialog pops up. If you wait about 4 seconds without typing anything then you see the yellow "sorry, that didn't work" error popup and the dialog closes. It does the same even if you enter the correct password quickly to try and beat the error message, i.e. you can't run the program at all. This problem happens with any program that requires authentication, not just synaptic (e.g. also happens with gparted).

I note that I can place synaptic in my launcher/dash (i.e. as a "favorite") and then I can start it ok, i.e. the dialog does not print that error message. It also does not happen if I navigate to the synaptic icon in the System Tools group. It only occurs if I start synaptic from the keyboard search, and there it happens every time.

I am using gdm rather than the default lightdm (due to the lightdm race condition bug on ubuntu) so I switched back to lightdm, logged in to gnome shell again, but the problem persists. The problem does not occur if I log in to Unity and start synaptic from the Unity dash, but note there that the authentication dialog is the traditional gnome su dialog, not the gnome-shell themed dialog where I see this bug.