1. fill column a,b,c, make grouped 2D column plot
2. open PD dialog, go to spacing tab, set width: col(b), subset to by column B, Gap =20%
3. right click on the plot, select upgroup
4. open PD dialog, go to spacing tab of 2nd plot
==> subset: none
==> width: col(c)
Fixed in Origin2019b.