The System Firmware Update - 10/26/2015 contains the drivers for the new Type Cover.I wasn't aware of any updates necessary to use the type cover. I merely connected it the way I connect the old one, only to discover it does not work.
Make sure to try the two button restart, holding volume up button while pressing power button for ~10 seconds. This worked to fix an undetected type cover, locked landscape orientation and undetected monitor via dock, which all occurred at the same time recently with me.
You'll get some options come up when you do this restart, just exit through to continue.
Has anyone else purchased the Surface Pro 4 type cover? My SP3 does not recognize it.