Why the program doesn't show any total displacement for result combinations?
The different representation of nodal displacements for a load case or a result combination is based on the following:
For a load case, the total member displacement u is calculated from the single displacements u-x, u-y and u-z.
For the result combination, however, it is possible that the individual displacements u-x, u-y and u-z come from different load cases.
Thus, no total displacement u can be calculated.
The individual maximum node deformations would have to be displayed separately, specifying the load cases that lead to those results, and then all again performed for max and min values.