Doorbell 2 randomly misses motion - new problem

I've had my doorbell for over a year and have only had occasional problems with it missing motion, but lately, for a month or so, it's been randomly completely missing obvious motion that should be detected. Not just deliveries, but my husband getting the delivery off the porch (he likes to make faces at the camera, in case I'm watching, so it should be picked up), or a neighbor who stood at my door, rolled up a flyer and tucked into my door handle (never got a notification of motion detected). These occurrences cannot be blamed on my settings, because I've had the same settings for over a year. There are still some instance where it does detect motion, but it's missing more than it's picking up. What's going on?