Hi, I've just found out that both the Trackpad and the TouchBar are seen as Magic Trackpads. The TouchBar is Magic Trackpad 1 and the Trackpad built-in is the Magic Trackpad 2 so I configured the gestures in the Required Trackpad Type (under Advanced) to use Magic Trackpad 2 Only. I don't have the problem anymore.
Regarding the Show Live View, TouchBar touches and gestures are shown!
Thanks for the fast response!