On first thought you might expect the sum of the above gains (Glazing + Wall + Floor + Roof/Ceiling + Ventilation + Infiltration + Equipment + Lighting + People + Solar) at design conditions to equal the Sensible cooling load. However a mix of convective and radiant gains cannot be expected to equal the (purely convective) cooling load.
To understand more clearly we need to consider the nature of the building thermal resistance/capacitance network used in E+ (actually E+ uses a response factor method by default but the same principle applies). For each zone, you can think of the thermal network as a single zone air node and a series of nodes for each surface. All zone convective gains are accumulated at the air node and radiant gains at the internal surface of each wall, window, roof etc. Conceptually speaking there is a resistance between the zone air and surface nodes and heat flows between them (through Rconv in the diagram below). The key to understanding the apparent discrepancy is that heat transferred to/from the surface nodes is not equivalent to heat exchanged at the air node. So the surface heat gains can’t simply be combined together with gains at the air point to calculate cooling system sensible gain.