Modal analysis is the solution of the Eigen condition and the solution are the Eigen values (Natural Frequencies) and Eigen Vector (the mode shapes). Note that the multiples of the Eigen Vectors are also a solution. There cannot be any specific stress involved with Mode Shapes as Mode Shapes are not displacements. The stress shown in stress page does not have any relevance as the stress is solved from the static loads representing the mass in the dynamic load case.
To have the dynamic stress you should be doing a time history or a response spectrum analysis. A mere Eigen Solution will not give you the dynamic stress that you are seeking for.