Where strips have already been drawn amendments made under the 'Hatches' interface may not be applied immediately. Generally, strips will need to be refreshed - the easiest way being to adjust the 2D exaggeration under the Location Manager - but even this does not always display the revised hatches. This can be because the hatch definition is already represented on a dedicated 'KNX' prefixed layer in the drawing. Removing the layer will allow the hatch pattern definition to be applied when the strip is refreshed.
The following video illustrates and explains the issue fully. It also shows how to take the steps necessary (mainly removing the layer) to address the issue: