So the answer seems to be that Arturia are too lazy to write their own drivers for their gear, and the native Win10 midi driver does not port share.
I managed to send midi from GuitarPro7 to EZKeys via LoopBe1. But it would be far better if both programs could just connect to the damn MiniLabII simultaneously.
I'm really disappointed about the Arturia Midi Control Center software not having midi out, so that I could at least send midi from the MiniLabII -> MCC -> an VSTi via LoopBe1, to actually hear and see what the controllers and pads I'm assigning are doing. As it is, the MCC hogs the controller all for itself...
It's ridiculous that I have to write the bindings on a piece of paper, close the instrument, open MCC, edit and save the bindings, close MCC, open the instrument, find out something is wrong, try and work out what's wrong without having MCC open, close the instrument, open MCC, adjust the bindings without being able to hear whether it's fixed the issue or not, close the MCC, open the instrument, find out it still isn't working for some reason, and go back to step one. Really, really poor and frustrating.
On top of that, the pads of the MiniLabII don't even match up with what's in the MCC - when I press pad 1 - 4, pad 5 - 8 are selected in the MCC. I have to click on the damn element with my mouse to select it. Also I'm not impressed with the pad response either - you have to hit them really hard to get 127 velocity. Further, I can't even use half the patches in Analog Lab because it's too CPU intensive for my laptop and there isn't a setting in the software to lighten the load. Lastly, you've got shitty customer support too.
It's been a bad experience, and I feel a huge amount of buyer's regret. This was my first controller, and will be my last from Arturia.
No doubt Arturia staff won't even read this, so it's really for future potential customers - research carefully before you buy an Arturia controller.