Yes the NVIDIA card is in the base. This is why the problem exists and why sometimes detach / reattach works.
However it is also the problem. Detaching/reattaching seems be one cause of 'losing' the card, meaning a restart or other intervention is needed. So anytime you want to use the primary feature of the book, you break the main advantage it has over a Pro. For it me it means I hardly ever remove the tablet, or turn it around as it will mean an hour of stuffing about to make it use the graphics card next time I need it. It should be seamless hand over, they advertise it as a seamless handover. This is now an overpriced and underpowered laptop, not a fancy 2 in 1 combo tablet.