Hulk buster unpredictable heavy behavior

Im playing hulk buster alot as 5* and 4* in eq and aw, after using sp2 against the wall on block, going for heavy attacks is so unpredictable and punishing. Most times it lands, sometimes range to short, or heavy just pass through opponent even after few heavy attacks, sometimes im getting interceped mid heavy. The heavy feels slow and the reach random as hb can leap forward abit or stay in place. After sp2 landing position is random as well under cercamstances.