Stick Up Camera not detecting movement through glass?

Hey there. Had Ring for a while and recently had been having some issues with vehicles being damaged when parked. Decided to buy a couple stick up cameras that I could put on the dashboard of my vehicles when parked outside (but in Wifi range) to pick up on any movement. Got one on the dash of my car aiming forward, and one on the backseat of my truck aiming backwards. Here's the weird thing. They work great. I can do a live connect to them just fine. But I'm not getting any recordings at all for movement. I can literally walk in front of the car with the camera looking right at me. With sensitivity turned all the way up. And it still doesn't activate. I left them in the cars all night, and while I could see cars driving up/down the street, the camera(s) never claimed to see motion.