Black screen when screen mirroring … but only from one device

latest Apple TV fully updated connected to LG TV. 8 devices in the household - 4 iPads various ages all on the latest iOS 16 including the security patch, 4 iPhones various ages and again on the latest iOS 16 with security patch. 4 apple IDs with one phone and one pad on each ID. Airplay works from all 8 devices in the house. Screen mirroring works from 7 of the 8 devices. The 8th device ( an iPad Pro 10.5inch) as of this morning sends the TV to black screen on selection of screen mirroring and returns to Apple TV display when deselected. I have reset all devices, reset network settings, reset all settings, wiped and re-installed the Apple TV. I have forgotten and rejoined the Wi-Fi with all devices. There is only one Wi-Fi present. But Clearly it’s not the Wi-Fi as airplay works and all the other devices can screen mirror and airplay. Also - and here is the killer - I can screen mirror with the 8th iPad to the iMac. So the only thing that consistently doesn’t work is screen mirroring from device 8 (and iPad) with the Apple TV. It’s really annoying but more, I’m pretty tech savvy and I can’t work this out.