Location finding (iOS Find My app) slow and non-refreshing

For the past several months, the normally ultra-reliable Find My app has stopped working effectively when using it to locate a member of my family using iOS device in LTE-land.

When I try and find my family member, Find My takes a long time to find them (often at least a few minutes), and when it does, usually isn't able to locate them with much accuracy (the accuracy is typically several miles wide) whereas in the past, it used to find them (usually) specific to a house.

Furthermore, Find My doesn't seem to update often. If it eventually finds my family member to within several miles, it may not update for 30-60 minutes -- not getting a more accurate pinpoint location -- nor noticing if my family member moves. Sometimes I try and locate them, get location data that's 60 minutes old, and before I know it, they're really in a completely different location, which hasn't been updated.

I don't think the problem is literally with the Find My app. (That's just where I see the symptom.) I think there's something wonky with the specific iOS device. Is there any way to reset these location services and maybe get it working properly again?