Dying From Fall Damage From 2 Blocks

People On My Realm Are Dying From Fall Damage When Jumping Down From 2 Or 5 Blocks.

Does Not Happen Every Time. Maybe Every Day Or Two It Happens To One Person So Didnt Test On Local Copy As It Would Take To Long..

The Heart Or Hunger Bar Is Full.. 

It Has Even Happen When In Peacefull Mode.