Water leaking through brick veneer

as you can see, the ledge has been retro-fitted w/flashing & its sealed w/silicon,,, the window cover'd w/plastic has been suspected of being the culprit of allowing water to penetrate the interior of the unit below,,, i know wtr's getting inside somehow but i'm unsure where/how,,, previous contractor used garden hose 3x but no stopping it & he got thrown off job.

the mortar doesn't seem particularly porous as, if it were, it'd be washed out by now (20yrs),,, the area in the detail shows the angled brick which protudes from the face veneer by about 1",,, no discernible weeps at the btm courses

usually don't get stumped - anyone have ideas ? tnx in adv, guys