Perspective Gantt Chart wrong labels along time axis

Hi all,
I've managed to create a Gantt chart following the IA tutorial:
I'm now trying to get rid of the wrong time labels that sometimes appear at the top of the chart, as you can see in the following picture

Sometimes those labels are not present (expected behavior!!), sometimes they are, sometimes they are in sync with the time axis at the bottom, sometimes not.

Any idea?

Thanks in advance, regards

Just found that that strip is deep nested inside the scrollbar element:
Any chance to hide that scrollbar element? I cannot find any ID or class attribute, I can use in a CSS rule.