I'm having the same issue with the same GPU's as you guys. Divinity Original Sin is the only game that won't recognize the dedicated graphics card. Manually setting it in NVIDIA control panel does nothing either.

I went so far as disabling my Intel GPU and then running the game. The game refuses to recognize the NVIDIA card and it seems would prefer to use Microsoft Basic graphics, which runs at a stuttering 2 or 3 frames per second.

A solution to this problem would really help. The game is playable on the Intel card but it's not particularly enjoyable.

I will send my report.zip to the support and see what they say as well.