HP touchpad works in 20.04, but not 18.04. Must use 18.04, but how to fix?

Disclaimer

I am working on an industrial robotics project that only works with ROS Melodic or Kinetic (ROS1) each of which is tried to a specific Ubuntu release. Please do not suggest using a different version or distro. It's not an option.

Issue

• Touchpad on HP ProBook 640 G8 works in 20.04, but not 18.04

I have to get this working on 4 machines total. 2 are ProBook 640 G8. 2 are ProBook 440 G8. I have not tried the ProBook 440 yet.

Info

I don't know what to include here, but I will add any info requested.

Ubuntu 18.04

bruno@bruno-ubuntu1804:~$ lspci -k | grep -A2 USB; echo "###"; lsusb | grep Synaptics
00:0d.0 USB controller: Intel Corporation Device 9a13 (rev 01) Subsystem: Hewlett-Packard Company Device 87ed Kernel driver in use: xhci_hcd
00:0d.2 USB controller: Intel Corporation Device 9a1b (rev 01) Subsystem: Hewlett-Packard Company Device 87ed
00:0e.0 RAID bus controller: Intel Corporation Device 9a0b
--
00:14.0 USB controller: Intel Corporation Device a0ed (rev 20) Subsystem: Hewlett-Packard Company Device 87ed Kernel driver in use: xhci_hcd
###
Bus 003 Device 004: ID 06cb:00f0 Synaptics, Inc. 

Ubuntu 20.04

bruno@bruno-ubuntu2004:~$ lspci -k | grep -A2 USB; echo "###"; lsusb | grep Synaptics
00:0d.0 USB controller: Intel Corporation Device 9a13 (rev 01) Subsystem: Hewlett-Packard Company Device 87ed Kernel driver in use: xhci_hcd
--
00:0d.2 USB controller: Intel Corporation Device 9a1b (rev 01) Subsystem: Hewlett-Packard Company Device 87ed Kernel driver in use: thunderbolt
--
00:14.0 USB controller: Intel Corporation Device a0ed (rev 20) Subsystem: Hewlett-Packard Company Device 87ed Kernel driver in use: xhci_hcd
###
Bus 003 Device 004: ID 06cb:00f0 Synaptics, Inc. 

Please add comments requesting more information (preferably including the CLI commands to get the info).

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