Doorbell Push Alexa Notification have stopped

I have a Video Doorbell 4 with hard wired Power Source.It is connected to Alexa via the Ring app and via the Alexa App. We have a variety of Alexa devices (Studio Echo, Echo and Dot's).Up until a few weeks ago it was working without issue. Someone would push the doorbell button and we would hear a notification on all Alexa devices. Now it doesn't. I have restarted all the devices. Uninstalled and reinstalled both Alexa and Ring Apps on my iPhone. I have also disconnected the amazon account from the Ring App and reconnected it. I have also disabled the Ring skill from Alexa and re-enabled. None of these appear to solve the issue.I have searched various threads but they either go cold without a solution, or one of the above solutions works for one person - but it hasn't for me. Please can you advise why notifications aren't being pushed to Alexa - only to the Ring app on my phone?