Yes same problem, need to re-connect to make it work again. annoying ! But also my external screen connect to the usb-c port (including power delivery to the mac) is only showing the mouse-pointer on a black screen. No picture! Need to re-connect to make it work again. also reboot does resolve this problem. It seems the drivers are not reloaded after waking up from sleep and only the default function will work from the drivers. Apple Please fix this!