Steps to reproduce:

• Take Shulker Box from the creative inventory
• Place the Shulker Box
• Use Pick Block on it
  You are given a new item.

The following is the item NBT of both items:

• From creative inventory:

  {Item:{id:"minecraft:shulker_box",Count:1b,tag:{BlockEntityTag:{Color:10b}},Damage:0s}}
  

• From using Pick Block:

  {Item:{id:"minecraft:shulker_box",Count:1b,tag:{BlockEntityTag:{Color:10b,Items:[]}},Damage:0s}}