Thanks for inquiring Aspose.Slides.
I have observed the issue share by you and like to share that Aspose.Slides export the report to presentation as it is available in report. I request you to please try using Aspose.Slides for Reporting Services 5.1.3 on your end first. If there is still an issue then please first export your report to Tiff or PDF and observe the text rotation effects in them. If the text rotation effect is available in PDF or Tiff but unavailable in generated presentation, then it is likely an issue in Aspose.Slides for Reporting Services. In that case please share source RDL, Data source for RDL in the form DML and DDL SQL statements for schema, generated presentation, generated Tiff, generated PDF and RPL export of the presentation
. We will investigate the issue further on our end to help you out.