Q: Find my friends has worked fine until recently when about half of my contacts show as "location not available". I know it is not something with my contact's individual accounts as it is happening for half of my contact list. Any thoughts?

I have the Iphone 5 and have had the "find my friends app" for months. It has worked fine until a couple days ago when about half of my contacts show up as "location unavailable". The other half still update as normal. I have closed, removed and re installed the app and it still does the same thing. The only thing that has been somewhat helpful is to delete the contact and then re add. This worked for one, but not for another (worked for one minute and then went back to "location unavailable"). Any suggestions on how to reset it or get it to locate the other half of the list?