Touchpad not working on HP Spectre x360

[jabrilm]

I've installed Ubuntu 18.04 on a new HP Spectre x360 convertible laptop. However, the touchpad does not work. It does work with a USB mouse though.

This is the output of xinput --list (with the USB mouse connected):

$ xinput --list
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ SIGMACHIP Usb Mouse id=10 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
↳ Power Button id=6 [slave keyboard (3)]
↳ Video Bus id=7 [slave keyboard (3)]
↳ Video Bus id=8 [slave keyboard (3)]
↳ Power Button id=9 [slave keyboard (3)]
↳ HP Wide Vision FHD Camera: HP W id=11 [slave keyboard (3)]
↳ HP Wide Vision FHD Camera: HP I id=12 [slave keyboard (3)]
↳ Intel HID events id=13 [slave keyboard (3)]
↳ Intel HID 5 button array id=14 [slave keyboard (3)]
↳ AT Translated Set 2 keyboard id=15 [slave keyboard (3)]
↳ HP WMI hotkeys id=16 [slave keyboard (3)]
↳ HP Wireless hotkeys id=17 [slave keyboard (3)]

And this is the output of lsusb:

Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 06cb:00bb Synaptics, Inc.
Bus 001 Device 003: ID 04ca:7086 Lite-On Technology Corp.
Bus 001 Device 005: ID 8087:0aaa Intel Corp.
Bus 001 Device 006: ID 1c4f:0032 SiGma Micro
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

What can I do to get Ubuntu to recognize the touchpad?

[jabrilm]

I should add that the touchpad works fine in Windows 10 and also within Ubuntu 18.04 running in a VM within Windows 10.