I can confirm that this item:
http://www.gearbest.com/usb-gadgets/pp_256041.html
Does NOT work OTG + charging at the same time. Tried every combination (power 1st, USB 2nd; USB 1st, power 2nd)
Getting kind of desperate, i can’t find one living soul that has a working OTG + Charging cable for Mi pad 2.
I’m beginning to think the problem is with the tablet itself.