Summoned items can't be picked up

/summon Item ~ ~ ~ {Item:{id:"minecraft:diamond_sword",Count:1}}

/summon Item ~ ~1 ~ {Item:{id:276}}

I summoned a diamond sword and can't pick it up. When I throw another diamond sword on it then it gets stacked and can be picked up. But I only get one diamond sword back.

Edit: With "PickupDelay" it didn't work too.