The Separation Range in your example shows 150,000 km, so as given the answer is "No."
However, that is the default range of it. When you bring up an old missile in the Missile Design window in Aurora, it automagically sets your Separation Range to 150,000 km. If your Separation Range is ACTUALLY less than that and less than 50,000 km that that's your problem right there. If it isn't than I have no idea, sans the Res 60 Active Sensors not seeing an enemy that is right on top of it because it actually weights like... what 125 Tons? Is that even small enough to slip by? I have no idea.