thanks for your response.
I turned on Show Touches and on my small iPad Pro are shown two fingertips when I undo. When I tip with three fingers not any blue point is there.
Four fingers work...4 blue points. Crazy...
On the 12“ iPad everything is fine, two, three or even four blue points.
The only difference is iOS. On the smaller iPad is iOS 12.0.1, the larger one still works with iOS 12.0.
Tomorrow we are going to update the large iPad and try again.
I will let you know then if there is a difference on the larger iPad then.