My AirPods aren’t showing up on Find My iPhone

I was trying to make sure I could use Find My iPhone for my AirPods, but they weren’t showing up on the app and website. My phone is on IOS 12.3.0. I checked the app was on, and it was. It turned off and on the app. Still nothing. I tried to have the AirPods in my ears, in the case, outside the case, with the case closed and opened. Nothing worked. Please help!