The tooltip data isn't loaded properly when the mouse lands on the item due to the horizontal scroll rather than moving moues manually. This behaviour is mostly noticed on touchpads due to gestures.

See stackblitz.

Steps to reproduce

1. Place the mouse pointer before any item on the gantt
2. Scroll to the right or left without moving the mouse so the pointer stops on the item

It's important not to move the mouse, as soon as any action like movement or click happens the tooltip loads the data.

See the attached video.