I’m experiencing exactly the same issue:
After setting up the Ring with the Echo Show 5, all works well – the Amazon and Ring accounts are paired, alerts come through straight away, no issues…
The only problem is it doesn’t last! Within a matter of hours, the Echo no longer sounds or shows anything on screen when the doorbell is pressed. I can still use voice commands to answer the door, so it’s not a connectivity issue or a matter of the Ring skill being disabled. No other settings are changed in the interim, do not disturb mode is disabled, and it is definitely set to announce on this device.
Has there been any progress on this at all? I only have the doorbell alerts activated, no motion control.