Cant share iCloud storage with family I am a family admin
I purchased a 200GB plan which allows for sharing
I sent the share notification to family members
I received the invitation as a push notification on the family member device
When I click it, it will take me to the Apple ID setting in the Settings app
When I click on iCloud and look at storage it is still maxed out (5GB of 5GB used) and my only options available under “Manage Storage” is to “Upgrade,” which then wants me to purchase a plan.




Note: I also cannot get purchased app sharing (not in-app purchases) to work
You need to contact Apple Support so they can "refresh your family members iCloud account". Dont tell them that specifically, but what can happen is that iCloud may not be acknowledging the change, and its something they can do on their end. 

Other questions for you to answer: 
Do you see that family member in family sharing? 
Is it only that family member? If not call Apple Support with the other parties present (physically or 3-way).
Do they belong to another family?