So incredibly frustrating, time consuming and costing. Big Sur update is a big ***** up if you have an external monitor set up. Signal appears to be going to it when you check system information but the monitor is not receiving signal, BLANK SCREEN. Contacted APPLE they said can't do anything. Known problem. Wait for update. They should ONLY release OS updates that work. This is pathetic. Service person was as usual nice...but didn't have a work around and offered nothing for the time I wasted trying to make it work, research the issue, and contacting them. Starting to hate Apple.