Hello,
I can ask my Echo Show 8 to show me all my cameras and it works just fine. Slow but fine. Are you able to setup an automation for it to show a camera feed on your Echo Show when an event happens?
I have the Unifi Doorbell G4 and have it where it announces someone is at the door on button press. I am now trying to get it to automatically show my doorbell feed when the button is pressed as well. Does this work for you or have you gotten your cameras to show during an automation?
Here is where I asked my same question in more detail.