Having much the same experience with Family Sharing as other people here. I have found a 'solution' that worked for me, but I have no idea why it has fixed things.
Setup: New iPod Touch, out of the box yesterday, and updated to iOS 8.1. I've set up Family Sharing yesterday, and added a new 'child account' for my kid. That account has been used for the iPod Touch.
Symptoms:
- iPod Touch can see and download music in iTunes. It shows up as being purchased by me. Songs play fine. Hooray.
- iPod Touch can see all the apps that I've purchased in the past, and can download them for free, but once they have installed, running any of them gives the 'This app is no longer shared' message, with an option to buy the app again. Going back to the store, the app is free, because I've already bought it. Installing again gives the same error message.
Things tried:
- Remove all the purchased apps, reinstall just one. Still doesn't work.
- Double check the app details on the store - they have 'Family sharing: Yes' in the details.
- Power off the iPod Touch, leave it off overnight. Try again in the morning, still doesn't work. Remove app, resintalll, still doesn't work.
- Sign out of the child account from the app store. Sign back in with the child account. Reinstall app... still doesn't work. Repeat a few times - sign out, sign in, delete, reinstall, delete, reinstall. Still get the error message.
Thing that worked:
- Remove all the purchased apps, install the Find My Friends app first. Hmm. It installed without asking for a password. That's different.
- The Find My Friends app runs fine, without the error message.
- Now installing a family shared app works. It runs fine, without the error message. Installing them still require the child account password (as expected), but they run now.
I've only tried a few apps, but they seem to be running.
I still think this is dodgy - why would installing the Find my Friends app before all others make other things work?
I'll try to post again if this 'solution' is permanent or just a glitch for now.