Attributes given by armor pieces do not stack with each other

4 separate custom armor pieces that each add attributes do not add on top of each other.
For instance, make an armor set with pieces:

Helmet: +2 armor, +5% attack speed

Chestplate: +6 armor, +10% attack speed

Leggings: +5 armor, +10% movement speed

Boots: +2 armor, +15% movement speed
(all attack speed attributes use the add multiplied base operation with a base of 4.0)

(all movement speed attributes use the add multiplied base operation with a base of about 0.1)

Equip Chestplate first, Then Leggings, Then Boots, Then Helmet.

The expected total armor is +15,

The expected total attack speed is +15%, or about 4.6

The expected total movement speed is +25%, or about 12.5

Instead, the values are taken not from the total percentage or amount but rather the latest equipped piece of armor that modifies that value. The helmet was put on last and overrides all of the armor to only add +2. The boots armor bonus is vacant but because they were put on after the leggings only the boot’s movement speed bonus is present.