I made a report with a couple of charts in it, but the x-axis labels of the chart puzzled me. At first I couldn't find where I can modify the x-axis labels to be in a 90 degrees angle in all of those charts. Some of the charts had labels rotated 45 degrees, some 90 degrees and some of the labels were just horizontal. Now that I have solved it I want to share it :) . I add terms used in Finnish language Report Studio 'cause I think those translations used in it are often strange.
[ 1 ] Click category axis / luokan akseli in the chart
[ 2 ] In the properties list under General / Yleinen modify Label control / Nimen ohjausobjekti property from Default / Oletus àAutomatic / Automaattinen
Voilà! All the rotation properties are shown and you are able to set label rotation, eg. allow 90 degrees rotation.
NOTE: this applies to legacy charts.