Family Sharing—3 Ask To Buy problems

I have two kids, each with an iPod Touch. Their App Store access is managed with Ask To Buy.

Problem 1: Kid 1 can download anything. I never get an approval request.

Problem 2: I get approval requests from Kid 2, but after entering my password in Sign In to Approve, the app is not approved and 5 seconds later I get the same Sign In to Approve message. I know my password is right because I can sign in and out of iCloud with it.

Problem 3: I'm not getting any approval requests at all on my iMac running 10.11. They used to come in via Notification Center, now nothing. I have to use my own iOS device to approve these requests. How can I get my Mac back on board.

Thanks for any help.