Video Doorbell 2 Not Detecting Motion at Night

We installed the video doorbell 2 the first week of June, and it detected motion at night. After June 29, it stopped detecting anything once it starts getting dark. We have seen people walk across our yard at night where it should detect their motion. It still works during the day, and I’ve been through all of the settings and troubleshooting. Any ideas or is it just defective?

Mine doesn’t work either which is frustrating as we have installed it to catch the person vandalising our property at night. I’ve gone to video settings but there is no night vision mentioned.