I am half way through building a garage, the frame is up the outside brick wall and roof tiles are on. I have a one brick step down. I had to have a termite barrier installed and the official supplier said it has to go from the top of the slab and lay on top of the first brick course, which I did. The bricklayer laid his flashing on top of the termite barrier and attached it to the frame. So far so good. Now with all the rain of the last couple of days I have water penetrating from somewhere and coming from under the wall frame where it sits on the concrete slab. Because I have not yet had the walls lined I still have access to the wall and frame. I cannot see anywhere where the water might be coming in. The only thought I have is that it is somehow coming in across the termite barrier.
Probabilities are high that the brick lug, the step down area, is full of mortar. Did your mason leave every 3rd brick out and clean the lug after he was finished? If the lug is full of mortar it will not drain. I assume you checked the weep holes.