Question

[FutureUmp]

Two Balls Two Strikes, ball hits batter in left elbow. PU says its a ball because he "leaned in" to intentionally get struck. I called time and asked for a repeat fo the call and he said same thing. I asked how could he call "ball" when batter was struck (his call, intentional) and that i thought it should be a strike three, batter out. The batter ended up walking and costing us a run. What is the correct call for this if he intentionally leaned in to be struck?

Thanks for an answer for what seems like a no brainer but I cannot find a rule.