Volume display does not update when changing default sink

On my laptop I often have two PulseAudio sinks, the on-board audio (alsa_output.pci-0000_00_1b.0.analog-stereo) and a Bluetooth speaker (bluez_sink.8C_DE_52_2F_AF_F3). I can choose the default destination for sound output using the "Sound" pane of System Settings, and I can separately change the volume setting of each sink using the "paman" application. When I adjust the volume using the sound menu, it affects the default sink. However, when I change to a different default sink, the sound menu does not update and continues displaying the volume for the previously-selected sink. Only if I change the volume setting for one of the sinks (e.g. using paman) does the sound menu update to show the new volume level.

To reproduce:

Find a system with more than one sound sink.

Launch paman and open the Properties window for each sink.

Also open the Sound pane of System Settings.

Set one sink to maximum volume and one to minumum.

Switch between outputs using Systems Settings, and note that the sound menu does not update to match the different volume settings of the two sinks.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: indicator-sound 12.10.2+14.04.20140401-0ubuntu1
ProcVersionSignature: Ubuntu 3.16.0-25.33~14.04.2-generic 3.16.7
Uname: Linux 3.16.0-25-generic i686
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: i386
CurrentDesktop: Unity
Date: Sat Nov 29 19:10:52 2014
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-motts-20100121-3
EcryptfsInUse: Yes
InstallationDate: Installed on 2010-06-09 (1634 days ago)
InstallationMedia: Ubuntu GNU/Linux 9.10 "Karmic" - Build i386 LIVE Binary 20100121-21:52
SourcePackage: indicator-sound
UpgradeStatus: Upgraded to trusty on 2014-08-15 (105 days ago)