Armor Trims Don't Work on Items (1.21)

another_example_item: 
  Id: iron_chestplate
  NBT: 
    Trim: 
      material: minecraft:iron
      pattern: minecraft:shaper

Tried using this example on the wiki to make sure and it still doesn't work, using Premium v5.7.2 ( build cf66ff23 ). All the custom armors I had for mobs worked back on 1.20.