anonymous

Debugging this issue was a pain, but Steam now requires you to send the source id in the header with the purchase finalize request. You can do this by adding a callback to the function when sending the request. 
 

That schema entry is pointing to a musickit_prefab prefab. Check the prefabs section for an item by that name, and use that as a base for the item's data.
I don't plan to decode every individual attribute onto the item object since there are tons of them. If you need to check the value of an attribute that isn't already decoded, you'll just need to decode it yourself.