Ok - this is very specific, but I’m looking for help. I have a 2011 Air with High Sierra. Working great as a web/MS 365 computer. Just set up 2 external monitors (1 via MDP and 1 USB). They both work when the clamshell is open, but when I close it, they immediately mirror each other. Also, the USB display has a lag with the mouse, but the MDP one doesn’t. I’m using a J5Create USB to HDMI cable.