parent text label and expanded text label in a graph

Hi all,

I am trying to display text in y-axis. It worked as I wished when displaying parent text. (see attached 'before expanded')
However, when i expand it, the text label in a graph become strange in a way that parent text rotated to 90 deg while sub text show ok (see attached 'after expanded').

Is there any way to display parent text and sub text at the same angle in the graph?

Thank you for your help in advance.