UDisks.EnumerateDevices() fails with Error.AccessDenied

Dmedia scans the connected HDD etc using UDisks.EnumerateDevices(). On the netbook I'm testing on, it works fine under Precise, but fails on Quantal:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dmedia/service/udisks.py", line 306, in monitor
    devices = self.proxy.EnumerateDevices()
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.AccessDenied: Rejected send message, 4 matched rules; type="method_call", sender=":1.86" (uid=1000 pid=2781 comm="/usr/bin/python3 /usr/lib/dmedia/dmedia-service ") interface="(unset)" member="EnumerateDevices" error name="(unset)" requested_reply="0" destination=":1.70" (uid=0 pid=2002 comm="/usr/lib/udisks/udisks-daemon ")

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: udisks 1.0.4-6
ProcVersionSignature: Ubuntu 3.5.0-5.5-generic 3.5.0-rc7
Uname: Linux 3.5.0-5-generic i686
ApportVersion: 2.4-0ubuntu3
Architecture: i386
Date: Fri Jul 20 09:43:32 2012
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha i386 (20120627)
MachineType: ASUSTeK Computer INC. 1005HA
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-5-generic root=UUID=83211506-ba35-430a-9880-308021cca93a ro quiet splash vt.handoff=7
SourcePackage: udisks
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/18/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0601
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: 1005HA
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: x.xx
dmi.chassis.asset.tag: 0x00000000
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer INC.
dmi.chassis.version: x.x
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0601:bd06/18/2009:svnASUSTeKComputerINC.:pn1005HA:pvrx.x:rvnASUSTeKComputerINC.:rn1005HA:rvrx.xx:cvnASUSTeKComputerINC.:ct10:cvrx.x:
dmi.product.name: 1005HA
dmi.product.version: x.x
dmi.sys.vendor: ASUSTeK Computer INC.