Incorrect Tooltips in Firefox

Hi,

Using Firefox 45.01 on Windows 8 I've noticed that the when hovering over a combination column & line chart, the tool tip that appears is showing values for the wrong column.

Eg:

If I have columns for categories A,B,C,D,E, when I hover over the bar for category "D" the text in the tool tip shows the label & value for category "C".

Has anyone else encountered this?

Thanks,

Paul