Ah well not solved back to unable to view cameras on iPhone XR Did observe one thing, if I run version . Then on the app select a camera, shutdown version 4 get signal lost. then start version 5, signal pick up and camera can be viewed. If go back to cameras then select another camera, it viewed ok....

Solved, setup > camera > hardware accelartion was set to Nvidia NVDEC disabled.

On reboot asked did wish to install update. Tested on iPhone app camera viewed instantly, enabled Nvidia NVDEC. Rebooted Blue Iris tried iPhone app cameras viewed instantly.

Issue appears resolved.

Today upgraded to Version 5, I have the app on iPad running IOS 12. Start up app connects Ok. can see the camera thumb nails and they update. When I select a camera takes about 15 seconds before camera view displays. Now I only checked on the iPad ..dumb. When I tried on iPhone XR running IOS 13.2.2...