I received mine a couple days ago too and it barely works. It is defective, likely as is yours, and I'll be returning tomorrow.
Seems the QA of the Touchpad on the XPS 9350 is utterly lacking given the amount of complaints in this forum regarding it.
I'm not quite sure whether mine is broken or not. The Trackpad works fine as long as I don't use the Trackpad-"Buttons". These only react after two or three clicks.
Got anybody an idea whether this is fixable with software or if it's a hardware error?