Trisquel 6.0 -> Menu gone after updates yesterday ?

Hi all,

I launched my Trisquel 6.0 x64 virtual machine yesterday evening. Since the update manager popped up and asked me to install some updates, I completed the update process, rebooted the VM and my menu in the "task bar" was gone.

I still can see my desktop with all relevant icons but the Trisquel logo in the lower left, which ususally launched the app menu is completely gone.
Also any symbol such as the audio mixer vanished.

Is this a known issues ?

I did not verify the issue with my recently set up Trisquel hardware box though.

Any ideas on this ?

TIA,
Holger