I just got the $1500 one of these with the Kaby Lake Core i7, 16GB RAM, and 512GB SSD today. From the first minute of usage, I've had this trackpad issue. It is extremely annoying. It feels like a cheap, rickety trackpad. I will try to replace it for something else. Ironically, I previously had a Surface Book, and it had software issues, and after it was replaced with a refurbished unit, I didn't try it again - I just sold it. This unit has gotten rave review on YouTube. Very disappointing HP.
I took the laptop back to Best Buy. Their team also immediately saw the loose trackpad, and took it back. I didn't take a risk of getting a replacement X360 because from what I've read on this forum, and a similar one for an earlier version of the X360, this loose trackpad issue is very common with one person having had to replace his laptop 5 times before he got one that didn't have this.
I hope that folks at HP are listening. What is otherwise a very nice device has this flaw that makes it feel very cheaply built, and not worthy of $600, let alone $1500. There are even YouTube videos out there on how to open the machine up and stick double sided tape under the trackpad at a certain place to diminish this issue.