Thinkpad P50 touchpad/trackpoint not responding in Ubuntu 20.04.1 when using Nvidia drivers

[Decio Della Fortuna]

Thinkpad P50 touchpad/trackpint do not work at all when Nvidia proprietary drivers are installed and the settings in the bios are set to discrete mode for GPU.
I have to use an external mouse to work.
Keyboard work fine.

Thinkpad P50 BIOS is at the latest version 1.62, Nvidia drivers are 440 Ubuntu tested.

decio@ncc-1701:~$ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 138a:0090 Validity Sensors, Inc. VFS7500 Touch Fingerprint Sensor
Bus 001 Device 003: ID 04ca:7058 Lite-On Technology Corp. Integrated Camera
Bus 001 Device 002: ID 046d:c52f Logitech, Inc. Unifying Receiver
Bus 001 Device 007: ID 8087:0a2b Intel Corp.
Bus 001 Device 005: ID 058f:9540 Alcor Micro Corp. AU9540 Smartcard Reader
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

decio@ncc-1701:~$ xinput list
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ Logitech M280/320/275 id=9 [slave pointer (2)]
⎜ ↳ Synaptics TM3149-002 id=13 [slave pointer (2)]
⎜ ↳ TPPS/2 IBM TrackPoint id=14 [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)]
    ↳ Sleep Button id=8 [slave keyboard (3)]
    ↳ Integrated Camera: Integrated C id=10 [slave keyboard (3)]
    ↳ AT Translated Set 2 keyboard id=11 [slave keyboard (3)]
    ↳ ThinkPad Extra Buttons id=12 [slave keyboard (3)]
    ↳ Logitech M280/320/275 id=15 [slave keyboard (3)]