Fitness app (Apple Watch)

A friend who, like me, has an Apple Watch sent me a sharing request on the fitness app. I’ve received it and it shows as a bubble with “1” in it in the app. In the sharing section of the app, there is an icon at top right of screen which is to send and accept sharing invitations. It seems to be indicating that my friend’s invitation is waiting but when I touch it, the whole app just crashes and closes. I’ve restarted my phone and tried to delete and reinstall app but seems it can’t be deleted. Any thoughts how I can clear / accept this invitation?