Stein Schoenflies conjecture for embedded homotopy 4-balls

Let $X$ be a compact Stein domain of complex dimension $2$, and let $B\subset X$ be an embedded homotopy $4$-ball bounded by a smoothly embedded $S^3$. Stein Schoenflies conjecture. Then $B$ is a standard $4$-ball. This extends the smooth four-dimensional Schoenflies conjecture to homotopy 4-balls embedded in compact Stein surfaces and is motivated by the construction of Stein trisections and holomorphic-disk reimbeddings. Its status is not resolved in the source.