XPS 15-9560 (2017) touchpad operates only as a mouse

Hi!

Some days ago, my touchpad lost its advanced functions. Right now, it is only operating as a mouse, meaning that gestures, scrolling, multiple finger moves etc. etc. are not recognized any more.

Maybe somebody can help me, or maybe someone has got the same issue.

I will describe my findings briefly:

The touchpad is not detected by the Dell Support Assist routine; it is not listed in the bios or anywhere else.

(I had a 90 minute session with the Dell hotline, but they could not help me. They offered to replace the touchpad, but I am quite sure that it is a software issue.)

In my hardware manager, I can find several suspicious entries, making me suspect a deep-rooted hardware conflict of some sort. One active entry is called "I2C HID device". It is highlighted with a "code 10" (cannot be started; "A request for the HID descpriptor failed"). Deactivating or deinstalling this device does not change anything (I once deinstalled all HID devices and the mouse, but nothing came of it. The drivers, Windows reinstalled automatically, were exactly the same, leading to the same conflict).The hardware ID of the device is *DLL07BE, which seems to be a touchpad (Synaptics, it appears).

If I look into the extended list of non-active devices in the hardware manager, I can see another (non-active) entry, saying "HID compatible touchpad". I can't see when the device has been removed, but the hardware ID is the same as above.

The hardware manager lists a mouse as well, although I do not have one plugged in (I have got a USB mouse in my office, which is connected to a thunderbolt dock; but right now, the dock is not connected). According to the hardware manager, It is active and working - and it has got the same hardware ID as above! *DLL07BE

My supposition is that the touchpad is for some reason recognized as a mouse, which overrides the other drivers. But why would that be? And how to stop it from doing that?

Any ideas would be greatly appreciated!