PROBLEM
You have wall that is not showing as cut - it is not showing any internal walls layers.
CAUSE
First check Detail Level is not set to Coarse.
Autodesk claims Revit displays any wall that has an unconnected height lower than 6 feet (1828.8mm) as if it is viewed from above.
But experiments I have done show anything below 2000mm will not display as cut.
SOLUTION 1
Instead of using the unconnected height parameter to define the height of the wall, set the wall so that it is constrained to the level above (using Top Constraint) and then set the Top Offset parameter to a negative value so that the value that displays for Unconnected Height (it will be grayed out, but will update) with the height of the wall. Making this change will overwrite the “low wall” behavior, but still give you the same height wall.
SOLUTION 2
Change the offsets in the View Range for the View Depth and the Primary Range’s Bottom to be 6 feet below the top.
e.g. if the wall is 1200 high, make the View Depth and the Primary Range’s Bottom values -630mm.
Alternatively change View Depth and the Primary Range’s Bottom to Unlimited.
If you don't want to change the whole view's view range draw a Plan Region over the wall and change the plan region's values.