In the presentation of model and result data of a vertical 3D model the different allocation of the coordinate axes has to be considered. Moreover, not all sections are shown as you might intuitively be expected.

Since the usual presentation of the free surface does not make sense in a vertical 3D model, the presentation of the free surface in a vertical 3D model requires a detour on the following procedure:

The Y-coordinates (= layer height) are saved as the attribute KKKK (Attributes Copy Attribute-wise...).

Then the attribute KKKK is subtracted of the calculated potentials (Attributes Import model / result data...) and stored on any node attribute (Attributes Computation Intercalculation...). The free surface is obtained as the contour lines of this attribute with value = 0.0.

Hiding of the results above the free surface is not possible.