Leap Bridge Steel - Diaphragm analysis assumptions in FEM models

How does Leap Bridge Steel treat diaphragm end connections for FEM models?  My analysis results only yield axial loading and all of my shears and moments have a value of zero, suggesting pinned ends are used within the software.  This is in contrast to running the same model as a grid analysis, which yield moments, shears, and huge axial forces. 

Thanks in advance!