If you have a textbox, then you add text seperated by a line break (using VbCrLf), the text alignment for all rows but the bottom will always be left aligned. For example, if you center the text in the textbox in the report, all rows in that textbox should be centered. However, after being exported to PPT/PPTX, only the last row in the textbox is centered, all other rows are left aligned.
This is easy to reproduce with the latest version of Aspose.Slides with SSRS2008:
a) Create a new report.
b) Add a textbox.
c) Add the following expression:
="row1" + vbCrLf + "row2" + vbCrLf + "row3"
d) Set the TextAlign property to "Center".
All three rows in this textbox should be centered. They are when viewing the report and when exporting to TIFF. But when exporting using Aspose.Slides this is not the case.