I just attempted the upgrade from 16.04 to 18.04 and have this issue as well.
Default Ubuntu desktop (gnome desktop on xorg)
Cintiq Companion Hybrid 13HD (DTH-A1300)
Since the update, I have no touch nor stylus input, nor are the hardware buttons detected when pressed.
In Gnome control center's Wacom Settings Applet, no stylus is detected, but the tablet is detected.
I cannot remap inputs or calibrate the stylus because they are not detected.
I just attempted the upgrade from 16.04 to 18.04 and have this issue as well.
Default Ubuntu desktop (gnome desktop on xorg)
Cintiq Companion Hybrid 13HD (DTH-A1300)
Since the update, I have no touch nor stylus input, nor are the hardware buttons detected when pressed.
In Gnome control center's Wacom Settings Applet, no stylus is detected, but the tablet is detected.
I cannot remap inputs or calibrate the stylus because they are not detected.