Martin's conjecture that real Blackwell determinacy implies determinacy

Let ${\mathsf{AD}}$ denote the axiom of determinacy and let ${\mathsf{Bl}\text{-}\mathsf{AD}}$ denote the axiom of Blackwell determinacy. Martin's conjecture.

${\mathsf{Bl}\text{-}\mathsf{AD}}$ implies ${\mathsf{AD}}$. Hence ${\mathsf{AD}}$ and ${\mathsf{Bl}\text{-}\mathsf{AD}}$ are equivalent.

Martin proposed this after proving that determinacy implies Blackwell determinacy. The claim is also posed as the paper's final open question, and its resolution is not indicated here.