Update: We now find that sometimes both phones do not receive doorbell ring, other times just one does and others they both work. I would suspect it is highly likely that a motion video is being uploaded but that does not excuse the fact that a doorbell press should still ring.
In normal operation you would expect a movement notification (say for the postman putting a letter in the mail box) but if he needs a signature then he will press the bell. So normally you may get a motion detection which you can safely ignore but if someone presses the bell you will almost certainly want to be notified, regardless as to whether or not a video is uploading
I have tried the Rapid app but it is not suitable as a replacement for the Ring app as it does not allow for personalisation of the sounds and has no setting as to whether or not overide do not disturb. As you can imagine my phone goes into do not disturb overnight and I don’t particularly want to be notified of movement events but would definitely want to be able to tell if someone is ringing the doorbell.
Probably related to this issue