Undetected movement

We have recently installed a Ring Doorbell 3 Plus however it is not detecting movement as expected. We have ensured the motion zones and settings are correct as we believe most movement is detected. The issue however is when we know movement has occurred, whether it be ourselves or delivery drivers, yet we can not see this on the footage. This happened at least 3 times yesterday when people came to the door and were not detected - which is the whole reason we installed the device in the first place. Could you please recommend a solution?