Ring Stick Up Cam battery motion problem

Hello I have a problem with my ring stick up cam that I placed outdoors. I have just recently purchased it 2 days ago and i believe that the motion sensor is not working properly! Sometimes it senses someone walking and sometimes it doesn’t ! This is quite disappointing as I already have a ring door bell that works really well which is what helped to buy the stick up cam. Please help me find solution on this issue. P.S I have changed the settings to the highest sensitivity. Thanks