iPad used as 3rd screen - flickering

Until today I have been presenting courses over Zoom using 3 screens. I use a MacBook, a monitor and an iPad. This allows me to see my presenter notes whilst delivering the training. Today the iPad started flickering to the point I was unable to use it. I then managed to stop the flickering by checking the cables but in doing so only the top half of the PowerPoint slide was displayed. Again I managed to resolve this by leaving and rejoining but the flickering started again…Has anyone else experienced this?