EDIT: Nevermind this, it isn't a bug. I just worded the command wrong.
First I made a sword with these data tags, and it appeared to worked just fine.
Later, I noticed the sword had disappeared.
The Age:-32768 data tag didn't work, and I believe I entered it correctly, but if I didn't please tell me. Otherwise this is a fairly big bug.
The exact command is:
/summon Item ~ ~-2 ~ {Item:{id:diamond_sword,Age:-32768,PickupDelay:32767}}
Your "Age" and "PickupDelay" tags are in the wrong location; you've set them within the "Item" tag, when they should belong at the root.