No gesture events from touchpad on Windows or Linux. Why?

I have recently added gesture UI to some of my apps: 2 fingered swipe, pinch/zoom and rotate. On my MacBook this works fine from the trackpad. On another laptop which has both a touch screen and a multi-touch capable trackpad, under both Ubuntu Bionic and Windows 10, the UI works fine from the touch screen but not from the trackpad. When I touch down 2 fingers I see MOUSEWHEEL events and that is all. There are no FINGER* or MULTIGESTURE events.

The Windows photo viewer happily supports pinch/zoom and rotate using this same trackpad.

Is there something I need to enable to make SDL deliver the necessary events or is this a bug or a deliberate omission?