Sorry to be a pain here, but this is a critical issue for us and our ability to generate reports. Could you please provide an update to when this may be resolved or what outcomes your development team have found with this issue. Given that this seems to have been in issue in past versions, this seems to be repeating for new versions of Aspose.
This seems to be more related to .ppt, We have converted the .ppt to .pptx, however the converted .pptx file format is causing formatting issues. If you have some suggestions to how the conversion from .ppt to .pptx could be made without formatting issues, that may help us in the immediate case, however ultimately the "Placeholder index must be between 0 and 7" being resolved would be ideal.