One example:

1. Make a line plot.

2. Open PD, enable fill area under curve in line tab, go to pattern tab, set fill color map to column B.

3. Uncheck follow line transparency, change transparency to 50, click OK.

4. Add color scale
   ==> transparency of color scale is not 50.
   This issue also exists like set colormap for scatter color for line and symbol plot, and set transparency of symbol to be different from line.