Motion and video not triggered with a delivery to the house

I have had my Ring doorbell 4 for a week or more and it has worked perfectly until today. Whilst I was out I had a delivery placed in my front porch, as requested, but the video doorbell did not pick up the delivery man coming to the door. There were no video events between me leaving the house and returning some 6+ hours later. Very worried that the whole point of getting the doorbell, to alert me when I am out of the house, is not always working. It has worked over mobile data on previous occasions when I have been miles away, so not sure why it missed this time. Any thoughts or advice gratefully received.