Our staff typically teach using duplicate screen mode to display the same image on the computer and board, What we are finding is that if they are displaying a PowerPoint presentation and freeze the board so that they can do some other work on their computer while the pupils use the frozen screen on the board. When they press escape to end the Powerpoint presentation the board or computer screen goes black. What appears to be happening is that when they press escape the screen mode is being changed away from duplicate mode.
Although this is happening frequently it doesn’t always happen and I am struggling to replicate it on a test setup.
Would it be possible for you to confirm the model number or product code that you are using as a board? Also, when you present the PowerPoint, on the Slideshow tab, could you try changing the monitor from Automatic to the Primary Monitor, and try to disable Presenter View? Does this allow for the primary display to remain in duplicated mode?
In addition to this, are you using the Office365 version of PowerPoint or an older version such as Office 2019?
Lastly, which operating system are you using with PowerPoint?