This is seemingly caused by the virtualbox drivers not yet having support to non-root Xorg sessions.
The workaround for now is to install xserver-xorg-legacy and/or virtualbox-guest-dkms
This is seemingly caused by the virtualbox drivers not yet having support to non-root Xorg sessions.
The workaround for now is to install xserver-xorg-legacy and/or virtualbox- guest-dkms