Why don't items show in TPlanner Header section?

I use a TPlanner item with a vertical time axis (Display properties) and a Header with planner.positions = 7 in order to display a Week Calendar. The time axis displays times form 7 to 18 o'clock (scaled by displayscale); item creation is no problem.

However, no item that begins/is out of the time axis range gets displayed in the grid.
On a previous test with tplanner i got the effect that such items got displayed in the grey top bar of the header (above grid, beneath Caption). The grey bar's size also scaled automatically (the items neednt be displayed full-view).

Problem: I'm missing that effect at the moment. Please tell me what to do (or how to modify display if neccessary) to guarantee that the user can't overlook out-of-sight-items. How do out-of-sight-items get added to the grey bar automatically again?

Thank you!

Additional constraint: i cannot use a vertical scrollbar - range of display must sort of be a fixed intervall, while at the same time cannot show the whole 24 hour intervall.

If you want to display items that are outside the range of the displayed time axis, you could put these items in the header. To do this, set PlannerItem.Inheader = true and make sure to increase Planner.Header.Height to ensure there is room for such items.

With respect to scrollbar, I'm not sure I understand your question. By default a vertical scrollbar should appear when the time axis height exceeds the Planner control height. Is it the vertical scrollbar you want to hide or does the vertical scrollbar not appear for some reason?

Excellent - PlannerItem.Inheader solved it!
Also no further uncertainty about scrolling.
Many thanks! :)