had exactly the same problem. The above-mentioned didn't help.
For me I had to install the synaptic driver from the terminal. Even I didn't need the driver before, I need it now..
apt-get install xserver-xorg-input-synaptics xserver-xorg-input-synaptics-dev-hwe-16.04 xserver-xorg-core
Before xinput didn't show the device. After installig the driver xinput ...