/replaceitem doesn't place armor correctly

Description
When using the /replaceitem command to give a player armor, the armor does not show up. The game will not display any armor points, it will not display the armor in the slot or on the player. Although I can’t place any other armor items in that slot, even though I also can’t remove the item. This remains the same even after running the same /replaceitem command multiple times. But when i use the /give command to give the same item, the item that I placed using /replaceitem suddenly appears, and can be used, removed, or replaced with another item. This is true even if I already have the item I want to place with /replaceitem in my inventory.

Steps to Reproduce

1: Run a /replaceitem command to replace one of the four armor slots with an armor item that would usually go in that slot

2: Check if the command replaced that slot with the specified armor item (it probably won’t)

3: Run a /give command giving one of the same item you wanted to replace the slot with

4: Check if the slot you wanted to place an item in is now filled

What I Expect to Happen

The specified slot should be filled with the specified item.

What actually Happens

The item placed in the specified slot does not show up until /give is used to give the same item.