iphone says location not available when sharing with family

it's almost always on their phone, not yours. on the phone you're trying to see, go to Settings > their name > Find My and check Share My Location is on, and that My Location says This Device. if it's set to an iPad sitting at home or switched off, you'll get location not available. location services also needs to be on for Find My, and the phone obviously has to be on with a signal. low power mode can make it lag.