Mobs with attack_knockback attribute don't apply knockback to players blocking with a shield

The attribute minecraft:attack_knockback doesn't seem to be working in a consistent way when applying knockback to attacks blocked by a shield. If a mob has any value of attack knockback above 0, the knockback applied to a player blocking isn't proportional to the attribute value. Normal hits work as expected (but for some mobs don't, see MC-269226).

This is not consistent with ravagers and hoglins/zoglins, which have an attack knockback base value above 0 and deal knockback to players blocking with a shield.

How to reproduce

1. Summon a husk with an attack_knockback of 5, switch to survival.

   /execute summon minecraft:husk run attribute @s minecraft:attack_knockback base set 5
   

2. The husk attacks you applying high knockback to you.
3. If you are blocking with a shield, the husk doesn't apply any knockback.

Expected result
Mobs with an attack knockback value above 0 would knockback players blocking with a shield, like ravagers and hoglins/zoglins.

Observed result
Mobs with attack knockback don't deal increased knockback to players blocking, despite normal hits doing so.