Why does Apple Watch Activity Sharing stop after a few minutes?

My mum and I both share activity with each other, however it works for a few minutes and then it completely stops. 

Both phones, both watches, have been synced, restarted, checked regarding correct log ins, contacts have been checked.

When I send my mum a 7 day challenge request it comes from an old Apple ID. 

Even though we both share to other friends with no problems. 

[Re-Titled by Moderator]