As the label positioning algorithm attempts to place the labels near the top of the bars and the bars value (>100) does not fall within the axis range the labels get cut off to some degree. To prevent the high value labels from getting cut I would recommend you to use code like this:
RadChart1.DefaultView.ChartArea.AxisY.ExtendDirection = AxisExtendDirection.Up;
As for the zero value labels, It is a known issue and will be fixed for a future version of the control. Please, accept our apologies for this inconvenience.
All the best,
the Telerik team
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