Did you check the combat log? It should show the rolls (which are made with advantage because you're paralyzed) and the hit calculations.
I did not, but even when rolls against an AC of 30 are made with advantage, the chance to hit me 4 times in a row (even with advantage) are so low that it's unlikely and probably didn't influence this.
Also, nowhere in the Hold Person description does it state you can now hit those under influence of Hold Person with advantage.
