Brand new 2018 MBP and I have it connected to a CalDigit Thunderbolt (2) dock. Got my 34" LG U-whatever connected to the hub through HDMI. When I turn it off, the laptop still thinks it's connected as I can move the mouse out of the screen of the Mac and I can still see the other monitor in Display settings. I'm guessing it's using system resources to power this external display, not good. Any ideas on how to tell it to disconnect?