From The Pavilion

30.4.Josephs to Lukaku : Direct hit and Lukaku was gone. There was never a single there. Lukaku turns it towards mid-wicket and sets off, Austin swoops down and under-arm flicks the ball at the stumps, he misses and Lukaku survives.

Should this go down as a missed runout?

Technically yes but it didn't come after a failed check when it probably should
I will go and fix it