I have a chart with two y axis. There are 5 datasets for the Y1 and one for Y2.
I can show/hide the datasets by clicking on the legend and it works for all 5 datasets of Y1 axis.
If I hide the only one of Y2 the whole chart disappears.
Using 1.9.2. it is working fine, but after using 1.9.5 this bug appeared.