The Stacked Bar, Stacked Area charts both allow axis-based and fact-based Reference lines. A single fact-bound Reference Line is drawn for summed stacked items.
A Pie chart cannot have any type of reference line.
The fact based reference line is always associated with a fact column. When the column is removed from the Chart data layout, the corresponding reference line is also removed. When the fact column is hidden or focused, the reference line is also hidden, or focused.
If the chart type is switched to another chart type, the Reference Lines is hidden. Switching back to the original chart type restores the lines.