Location Sharing - Cannot See Child's Location

Hi, we turned on the Location Sharing on my 16 year old's iPhone 12 Pro Max yesterday. I could see his location then. Today I checked in my Family Location Sharing tab and saw that he wasn't seen anymore. We checked his phone today and he has kept his Location Sharing open to my view, but isn't viewable in my phone. What could have happened here? Any suggestions? Thanks.