The Knockback enchantment on spears does not work if the spear is in your off hand

Steps to reproduce the issue:

Spawn 2 armor stands and give yourself a knockback enchanted wooden spear.

Charge attack the first armor stand with the spear in your main hand. Notice how far it goes. Expected result

Charge attack the second armor stand with the spear in your off hand. Notice how it doesn’t go as far as the first. Actual result