Sidecar shows blank screen. Unless I reboot
My iPad shows this blank screen after it disconnects due to poor connection and I start sidecar back up. After rebooting the computer, and connecting with Sidecar, the problem is resolved.
I don't want to keep rebooting, however, every time this happens. So far, everything I've read refers to toggling 'Mirror Displays' as a potential solution. This doesn't work for me.
Go to display preferences > arrangement > tick and then remove the tick from mirror display option. For more info see here