We are sorry to hear that you have this issue. We’ve checked your “test.PDF” file and were not able to reproduce the reported issue, as it is depicted on the screenshot. We tested it in the latest version 2.9.1 of the GroupDocs.Viewer for .NET in both image-based and HTML-based modes. We also tested it in the GroupDocs.Viewer for Cloud Apps. In all cases the document rendering is okay.
Please give us more details about this issue. Which version of the GroupDocs.Viewer you have used? With what code of the GroupDocs.Viewer widget?
Thanks and waiting for your reply.