The Enderdragon doesn't show the 'Glowing Effect' (name of effect that the new spectrall arrow gives), and if you give the Enderdragon the effect with a command than the effect is displayed weird/incorrect

What I expected to happen was:

• when shooting the dragon with Spectral arrows: that the dragon whould get the effect
• When giving the effect to the enderdragon with command: that it whould work and whoud outline the dragon normally

What actually happened was:

• Arrow: I damaged the dragon, and the dragon didn't got the effect
• Command: The dragon it wings will show (outline) as squares (instead of outline-ing the correct shape of the wing. And the Beam that comes from the EnderCrystal is outlined as well, so that whould mean that the Beam of the Crystal whould belong to the textures of the Enderdragon. (if this texture would get seperated > so won't belong to the texture of the Dragon nor the Crystal < than it whould be a cool thing for mapmakers.)

Steps to Reproduce:
Arrow:
1. Go to the end (seed doesn't matter)
2. (easiest is in creative) grab spectral arrows and a bow
3. shoot at the dragon
4. If you hit the dragon you'll hear the sound effect
5. You don't see the effect (glowing effect)

Command:
1. Go to the end (seed doesn't matter)
2. Find the Dragon
3. Type this command in the chat: /effect @e[type=EnderDragon] minecraft:glowing
4. You'll see that the Dragon it wings will be incorrect outlined (squares)
and that the Beam of the EnderCrystal will get outlined as well.
5. If you cant see the enderdragon clearly, you can summon one without it's AI, so the Dragon will stand completely still. After that repeat step 3.

The Screenshot I've included shows the Bugg (with the command)