I'm seeing this message logged now: "Windows cannot store Bluetooth authentication codes (link keys) on the local adapter. Bluetooth keyboards might not work in the system BIOS during start-up" (Event ID 18, BTHUSB).
Also, in the Device Manager tool, I see the mouse listed under Bluetooth, and it says, "This device is working properly." Which of course it isn't. And under the events tab there is a message that reads: "Device BTHENUM\Dev_DCA904069256\8&358a825e&0&BluetoothDevice_DCA904069256 requires further installation."
I tried reinstalling the boot camp s/w but it doesn't do anything as the drivers are already installed and up-to-date.
Similarly for the keyboard, it says "Device BTHENUM\Dev_D4DCCD7D8EEB\8&358a825e&0&BluetoothDevice_D4DCCD7D8EEB requires further installation."
Looks like MS broke Bluetooth somewhere along the way. I also turned on/off the BT collaboration for the Wi-Fi adapter and that didn't seem to make any difference.