If any of you, as I was, are experiencing a bug where AGM-65s (and now the AGM-88 in the beta version) mounted on the outboard under wing pylons (stations 2 and 6 IIRC) do not disappear when fired, well i have a solution.
I deleted the fxo & metashaders2 folder from C:\Users\<username>\Saved Games\DCS (or DCS.openbeta as appropriate) folder. Then I Repaired DCS World from the Windows start menu.
Ran a mission and now both AGM-65 and AGM-88 do not leave phantom missiles on outboard pylon when fired!
To be clear: the bug behavior is weapons fire, track and (sometimes!) hit targets, disappearing from the stores page so they cannot be selected and weight and trim are affected accordingly; however, the 3D model remains on the pylon, unless emergency jettisoned.