Unable to set "LeftHanded" to "1b" for piglins

The bug

Unable to set "LeftHanded" to "1b" for piglins.
Still use right hand to hold items or weapons.

How to reproduce

1. Summon a piglin with a weapon and left handed:

   /summon piglin ~ ~ ~ {LeftHanded:1b,HandItems:[{id:iron_sword,Count:1}]}
   

   → Notice that the piglin is still holding the weapon with it right hand.

2. Use the following command:

   /data get entity @e[type=minecraft:piglin,distance=..3,limit=1]
   

   → Notice that LeftHanded is still 0b