I have experienced a bug when using Kangaroo. When I use the pressure plugin, the geometry only exists in the perspective window. I type show all and it says nothing is hidden. It isn’t just hidden it is GONE. go to another window and try zoom to extents and it cannot find geometry. I select a point in perspective and I see the white cursor in the other three windows but nothing is there. I delete the three windows, restore them, and the geometry is back.
The bug here is actually a display one not part of Kangaroo.
Whenever a point in Grasshopper gets far enough from the origin, the preview display completely stops working until you refresh the viewports (I usually just click the 4-viewports button).
With pressure, because it is proportional to area, it can cause objects to inflate indefinitely if it is strong enough to overcome the tensile resistance of the mesh. This is physically correct for a constant pressure.
If you want a pressure force which diminishes as the volume increases, so the mesh tries to reach a target volume, then use the ‘volume’ goal.