The bug

If an Ender Dragon flies through a shulker box, the shulker box will be destroyed without dropping anything, leading to the loss of items inside. This is inconsistent as shulker boxes always drop from explosions (though the item may be destroyed by subsequent explosions), and breaking a shulker box with items in Creative mode drops it. In addition, chests destroyed by the Ender Dragon still drop their contents.

To reproduce

• Ensure that gamerules doTileDrops and mobGriefing are enabled
• Summon an Ender Dragon, or visit the End and spawn it
• Place shulker boxes with items inside
• Teleport the dragon to yourself with /tp @e[type=minecraft:ender_dragon] @s