Hi there!
https://jsfiddle.net/Cortez/hntrxmzw/ (Treemap)
https://jsfiddle.net/Cortez/f854x6ge/ (Heatmap)
as you can see - tooltips are rendered invalidly. Try switching 'tooltip.outside' to false and you will see that tooltips start to render correctly. Happens only for Stock chart constructor.
Can you confirm it is a bug for I could open a GitHub ticket?