The principle of Invert function from Mathematics menu significantly differs from the color palette Inversion, which can be called with a button on the image toolbar to the left of the image. When you select Invert command from Mathematics menu or press the button

the image data transform: the entire range of values from minimum to maximum is rewritten and assigned to image points in reverse order. The point at which there was the maximum value will be minimal after the inversion, and those whose value was 1 nm less than the maximum, will be at 1 nm above the minimum. Thus the palette remains unchanged, and surface topography changes.