Hello Papka__,
I know my question has little to do with your post, but I reached this post trying everything possible to fix my issue with my mi pad2.
I am having problems with the USB MTP, it only works when I reboot the MiPad with the USB connected to the PC, If I unplug it once It wont work anymore and will only charge the MiPad. Windows does not make the typical noise when you plug a USB device.
Tried with other computers, all versions of windows, virtual machines , etc, etc, etc, reinstalled hundred times different roms and there is the issue.
In Fastboot mode works the USB port works OK, it only happens when it boots to Android.