Don't try to loot keystone from mail because it will vanish if you have 1 in bags already.
My current keystone;

Keystone that I restored and was destroyed whileago;

Also key in mail has affixes from week it was destroyed. Haven't picked it from mail since I want to push my 12, mate from guild advised to not even try to pick it up since his vanished with error that item already exists (assuming it was caused by his key in bags). So i need someone to test further.
Definitely needs some more testing. So if anyone wants to play with this please report back your findings.