Both flashback sessions work ok here, all the indicators show up & work.

Maybe go to ~/.cache & delete the upstart folder.
Then log out/in & see what shows up in ~/.cache/upstart/ gnome-session.log & dbus.log

fresh dbus.log here right after login
Activating service name='org.ayatana.bamf'

** (bamfdaemon:10750): WARNING **: Couldn't connect to accessibility bus: Failed to connect to socket /tmp/dbus-ijjneDIfoy: Connection refused
Activating service name='org.gtk.vfs.Daemon'
Successfully activated service 'org.gtk.vfs.Daemon'
Successfully activated service 'org.ayatana.bamf'
Activating service name='ca.desrt.dconf'
Successfully activated service 'ca.desrt.dconf'
Activating service name='org.freedesktop.IBus'
Successfully activated service 'org.freedesktop.IBus'
Activating service name='org.gnome.GConf'
Successfully activated service 'org.gnome.GConf'
Activating service name='org.gtk.Private.UDisks2VolumeMonitor'
Successfully activated service 'org.gtk.Private.UDisks2VolumeMonitor'
Activating service name='org.gtk.Private.AfcVolumeMonitor'
Successfully activated service 'org.gtk.Private.AfcVolumeMonitor'
Activating service name='org.gtk.Private.MTPVolumeMonitor'
Successfully activated service 'org.gtk.Private.MTPVolumeMonitor'
Activating service name='org.gtk.Private.GPhoto2VolumeMonitor'
Successfully activated service 'org.gtk.Private.GPhoto2VolumeMonitor'
Activating service name='org.gnome.panel.applet.IndicatorAppletComple teFactory'
Successfully activated service 'org.gnome.panel.applet.IndicatorAppletCompleteFac tory'

(indicator-applet-complete:10918): Gtk-CRITICAL **: gtk_accelerator_parse_with_keycode: assertion 'accelerator != NULL' failed

** (indicator-applet-complete:10918): WARNING **: Unable to parse mouse modifier '(null)'

Activating service name='com.canonical.indicator.printers'
Activating service name='com.canonical.indicator.sync'
Activating service name='com.canonical.indicator.application'
Activating service name='com.canonical.indicator.datetime'
Activating service name='com.canonical.indicator.power'
Activating service name='com.canonical.indicator.sound'
Activating service name='com.canonical.indicator.keyboard'
Activating service name='com.canonical.indicator.session'
Activating service name='com.canonical.indicator.messages'
Activating service name='com.canonical.indicator.bluetooth'
Successfully activated service 'com.canonical.indicator.sync'
Activating service name='org.gnome.ScreenSaver'
Successfully activated service 'com.canonical.indicator.messages'
Successfully activated service 'com.canonical.indicator.session'
Activating service name='org.gnome.evolution.dataserver.Sources1'
Successfully activated service 'com.canonical.indicator.datetime'
Successfully activated service 'com.canonical.indicator.application'

(indicator-applet-complete:10918): Indicator-Applet-Complete-CRITICAL **: entry_removed: assertion 'menuitem != NULL' failed
Successfully activated service 'com.canonical.indicator.sound'
Successfully activated service 'com.canonical.indicator.bluetooth'
Successfully activated service 'com.canonical.indicator.power'
module-cache-reaper-Message: Scanning data directories
module-cache-reaper-Message: Scanning cache directories
Successfully activated service 'org.gnome.evolution.dataserver.Sources1'
Successfully activated service 'com.canonical.indicator.printers'
Activating service name='org.gnome.evolution.dataserver.Calendar4'

(indicator-applet-complete:10918): GLib-GObject-WARNING **: g_object_disconnect: invalid signal spec "signal::show"
Successfully activated service 'org.gnome.ScreenSaver'
Successfully activated service 'com.canonical.indicator.keyboard'
Successfully activated service 'org.gnome.evolution.dataserver.Calendar4'
Activating service name='org.gtk.vfs.Metadata'
Successfully activated service 'org.gtk.vfs.Metadata'
Activating service name='org.gnome.zeitgeist.Engine'
Activating service name='org.gnome.zeitgeist.SimpleIndexer'
Successfully activated service 'org.gnome.zeitgeist.Engine'
Successfully activated service 'org.gnome.zeitgeist.SimpleIndexer'
...irrelevant