This has been discussed many times already: GSX doesn't have any notion of the outside scenery, the only information it has comes from the AFCAD so, there's no way for it to know if there's a building or not.
Which is why, there's an option to set the Maximum marshaller distance in the parking customization feature. This should be set to the highest possible value, before the marshaller disappear behind a wall. And, since the marshaller distance is calculated depending on the cockpit height, it's safer to test it with a 747.
