Highlight station not highlighting areas

When "Highlighting Stations" we used to have everything from the valve downstream to the area treated being highlighted. Recently, on all of our projects, many of the areas which are indeed connected (as proved through Edit Equipment and the lateral shows the flow) are not highlighted. What's up? I've noticed that it sometimes happens after we have modified that area and redefined the area. But sizing laterals does not change the result. It still is not shown as being part of the area served by the valve.