Armor stand held item

Setup:
place down a command block set to repeating and always active with command:

data merge entity @e[ limit= 1, sort= nearest, type= armor_stand] { ShowArms: 1b, HandItems: [{ id: "minecraft:blue_dye", Count: 1b, tag: { dummy: 1b, display: { Name: '

{ "text": "dummy"}

'}}},{}]}

place down another command block set to repeating and always active with command:

clear @a minecraft:blue_dye{ dummy: 1b}

set keepInventory to true (this makes the bug more consistent)
kill the player

try to grab the item from the armor_stand

The first time after a death, this makes a ghost item in the player's inventory that disappears after either opening the inventory or clicking on the item in inventory.

The armor stand will still be holding an item (you can check it's data with commands), but the item will not display. Killing the player makes the item held by the armor stand display again.