This picture has been taken upward inside the spandrel. The brown board is a glass, the white members are the mullions.
It shows one of most popular deficiencies: the gap in the gasket corner.
The new installed gaskets have a tendency to shrink, that's why they shall be cut with extra spare length. 
It is my experience that unfortunately this simple task is usually entrusted to the least experienced employee and the outcome may vary.
In a concealed location like this one, the leak investigation is a particularly difficult task because the water entries into the closed spandrel insulation, saturates it and travels inside the room thru the firestop to finally show up on the wall or soffit.  In order to track its origin, the investigator has no choice but to tear down the wall board or the soffit and get close enough to spandrel.  Usually at the time the destructive investigation starts, the furnishing is already devastated because of the leak and first investigation attempts undertaken by the building maintenance staff.

A designer should specify vulcanized gasket corners, which are idiot-proof.