Motion sensor not working properly at night

Newly installed, works well in daylight detecting motion and recording detected events at 20+ feet. At night have to be almost up to motion detector ie withing 5 or 6 feet before it detects motion and records the event. Sensitivity setting is maximum. Any advice please?

Although a lot of us can assume what it could be but I would think to contact the Eufy Helpdesk as the camera is pretty new.