I've been through an encounter that included something like 3 ghouls. While my character could evade most of the attacks because of the AC bonus (level 3 Path of the Beast barbarian, Tail transformation), my DM ruled that I still had to make the save against paralysis, as it was not related to whether the attack landed or not.
RAI, I think the save would only be needed if the attack landed, as technically you don't hit when an attack roll is lower than the target's AC, so we can assume there was no contact from the attacker to the attacked, or it was ineffective somehow and thus did not deal its damage, like hitting a shield or stopping on a piece of armor.
But I want to know if the save is needed per RAW.
Does the target of a ghoul's claw attack have to make a Con save to avoid being paralyzed only if the claw attack hits?