Items with trim patterns always display the same pattern in the inventory

When adding a custom trim pattern with a data pack and resource pack, the entity armor model looks correct, but the inventory item always uses the sentry pattern, with no way to change this.

How to reproduce

1. Download and enable the attached data pack and resource pack
2. Open a new world (/reload doesn't work for trim patterns)
3. Give yourself an armor piece with the new Stripes pattern, either by using sticks as template in a smithing table, or with this command:

   /give @s minecraft:iron_chestplate{Trim:{pattern:"example:stripes",material:"minecraft:redstone"}}
   

4. Notice that the armor model is renderer correctly, but the inventory item has the wrong pattern.