Unable to locate a lost family member's iPhone linked to family sharing using FindMy.

I have family sharing set up for all three of my kids. I have location sharing on with each device and have it locked to where they can't change it. However, my son left his phone on the bus yesterday when I went in to locate his device I realized his phone is showing up under people in Find My but not in the device location for me to mark it lost or anything. I tried going over screen time activity but it continuously load without reflecting an update. I sign into his iCloud and Apple is, I see his device is up to date. But I am not able to report it lost because even when signing in under his information I'm not able to report it lost, lock it nothing please advise

[Re-Titled By Moderator]