Q: Previous to iOS 9 I was able to approve these and then use Touch ID to confirm. Now it always wants a passcode and will not allow Touch ID why?

Settings - Touch iD and Passcode - (Use Touch for) - App store and iTunes - toggle to Off

Then reboot phone - no data loss - hold down off/on and home buttons till you see Apple logo and allow normal boot up

Then back to Settings - - Toggle to ON

See if that helps

(1114)

I'm having the same issue, unable to approve family share purchases with Touch ID. It only prompts for password, no option to use Touch ID since updating to iOS 9.  I tried the procedure recommended above and it did not work.

Looks like they fixed this with 9.2.1