Yes, the indicator plugin log can be found in
Log file location
The file location may be slightly changed in newer releases of Xubuntu. In Xubuntu 15.04, the location is
$HOME/.cache/xfce4-indicator-plugin.log and the example content as below.
DEBUG libindicator-plugin Looking at Module: libapplication.so
DEBUG libindicator-plugin Loading Module: libapplication.so
DEBUG libindicator-plugin Load indicator: libapplication.so
DEBUG libindicator-plugin Looking at Service: com.canonical.indicator.messages
DEBUG libindicator-plugin Loading Service: com.canonical.indicator.messages
DEBUG libindicator-plugin Load indicator: com.canonical.indicator.messages
DEBUG libindicator-plugin Looking at Service: com.canonical.indicator.sound
DEBUG libindicator-plugin Loading Service: com.canonical.indicator.sound
DEBUG libindicator-plugin Load indicator: com.canonical.indicator.sound
DEBUG Indicator-Application Connected to Application Indicator Service.
DEBUG Indicator-Application Request current apps
DEBUG Indicator-Application Building new application entry: :1.29 with icon: nm-no-connection at position 0
DEBUG libindicator-plugin Entry added for io=libapplication.so
DEBUG libindicator-plugin Entry added for io=com.canonical.indicator.sound
The older log files are found at
$HOME/.cache/upstart and kept separately as Gzip compressed files for each type of indicator. I had confirmed this for 14.04, but not sure whether this is still true for 15.04 and newer releases, because I only ran above output from Live USB.
In other words, the older log files are only found in Xubuntu that has been installed to a local machine. The Gzip compressed files are likely not to exist on a Live system.
Sound Settings do nothing
Based on the output from
env | grep SESSION, the session is
xfce for the current user. That is the reason why the "Sound Settings" does nothing.
This is also a known issue affecting 14.04 release, which was filed as Bug #1359249 on Launchpad in late 2014. Typical users wouldn't notice this, unless the user selected "Xfce Session" instead of "Xubuntu Session" before logging in to the Desktop.
Select "Xubuntu Session" before logging in to the Desktop. Then, on Xfce panel, click the Indicator Sound icon > Sound Settings... to open the Volume Control window as usual.