Hi Nguyen,
We can reproduce the reported scenario at our end. By default labelIntersetAction is “trim”. So that’s why, when labels intersect with each other, it get trimmed, even if you are using labelRotation. We suggest you to set labelIntersectAction to None and then use labelRotation as of now and also we have logged a bug report for “When label rotation is 90, primary x axis labels are not properly placed”, we will fix this issue and the fix will be included in the next patch release which is expected on 17 July, 2018.
Please let us know if you need any further assistance on this.
Thanks,
Baby.