Camera Remote App on Apple Watch Ultra leads to a black preview screen
My Apple Ultra Watch (1) is running the latest OS (11.0.1 at time of writing) whilst my iPhone 16 Pro Max is - likewise - running the latest OS (18.0.1 at time of writing). When I open the Camera Remote app on the watch, a black screen appears rather than the expected feed from the iPhone's camera. I am able to trigger a snapshot (from watch) but not see it in the preview (which is the purpose of a Remote App). The matter is resolved when I restart watch and/or phone, but then the issue returns after a while.
The same issue occurred with my iPhone 14 Pro Max with identical behaviour indicating that this is not a hardware issue per se.
Any help is greatly appreciated.
Apple Watch Ultra, watchOS 11