If two shulkers are in the same block, hurting them does not show the damage tint

When placing a floating noAI shulker inside of another one, it doesn't seem to show the red damage effect when hit.

To reproduce

1. Start by spawning a floating noAI shulker by using the following command:

   /summon minecraft:armor_stand ~ ~ ~ {Passengers:[{id:"minecraft:shulker",NoAI:1b,Peek:100b}]}

2. Then break the armor stand so the noAI shulker can act as a floating block.

3. Now repeat these steps again in the same position, break the armor stand and you will have 2 noAI shulkers floating

4. Try and hit the shulker

Observed behaviour

The red damage effect cannot be seen.

Expected behaviour

It should be seen even if the 2 shulkers are merged.