Models of mobs becoming see through

I thought everything would've just rolled out normally with a normal zombie riding a spider.

The zombie rode it with no problems when the spider was visible, when i gave it invisibility, the zombie started to go transparent.

I triggered it by:
1. Doing a summon command with a zombie.
2. Give it a {Riding:{id:Spider}}
3. Now give the spider invisibility if no transparency happens when visible:
{Riding:{id:Spider,ActiveEffects:[

}