Hello Wu,

Thank you for the provided information. 

The reported behavior is expected in a scenario with a single data point. This happens because by default the chart calculates the range of its axes automatically based on the plotted values. When you have one bar or bars with close values, the chart will calculate such range that the difference between them is visible. However, because the default origin value of the bar series 0 the bar could go out of the viewport. So, for example, the range could be calculated between 5 and 10, but the origin is still 0.

To resolve this you can use two approaches.
- Set the Minimum property of the axis to 0. 
- Or set the OriginValue property of the BarSeries3D to a value different than 0. You can get it based on the axis' range.

I hope this helps.

Regards,
Martin Ivanov
Technical Support Engineer