Apply scaling to chart with two series?

I have a network IO graph which works well but when backups occur, the lower “out” graph completely drowns out the “in” bandwidth until that burst works its way off the chart.

If I change the scale to log (base 10) the lower graph disappears. Is that as designed? Can you not apply scaling to a graph with a negative-y transformation on a series?

Not supported. There’s an open feature request for that