In the case of the tooltip normally being below the mouse, at the bottom of the chart it looks like you have some logic to move it above the mouse so it still shows in the chart. This works great, but we are looking to have the tooltip above the mouse normally, but we it appears there is not any logic to push it below at the top of the chart, see image below.
Our normal tooltip (mouse is hovering over smaller task)
At top of Gantt (mouse is overing over red task that it’s covering up)