I know this is an old thread, but it seems that the Family sharing "ask to buy" still is buggy as ever. First, I have two daughters, one of them bought a game (Octagon...), ask to buy, I get the notification on my iPhone, tried to approve it, a blank screen with "cancel" on the top left, and "loading.." animation on the middle, and nothing else, and waited forever, it's just stuck in that loading state. Click cancel, and basically the notification is gone and app download is declined. Notification also didn't show up on my Macbook pro. I asked her to try again, while I was logged in on my Mac, and the notification showed up on both my Mac and iPhone. Again I tried approving on my iPhone, same thing, hangs on "loading". But since I saw the notification on my Mac, tried it there, works just fine, I was able to approve the Mac App store game.
Now my second daughter wanted to download the same game. She is not seeing that the game is already purchased by her sister (which both of them is part of my Family sharing). She tried "ask to buy", i saw the notification on my phone, this time again, not showing up on my Mac. Tried to approve again on my iPhone, hangs again on "loading". But this time, since I can't see the notification on my Mac even when I am online, I can't approve the purchase of a Free item, which another family member already purchased. Even if we try again several times. Same experience.
I also tried approving on my iPad, the same happens... loading... forever.