Thanks for providing the sample file. We investigated the issue at our end and found that the back-end GroupDocs.Viewer API is rendering the Tiff file without any issue (see results). However, the issue might be occurring when the rendered pages are loaded in the front end application. Therefore, we recommend you to check your front end application for this issue.
Furthermore, we can see that the source code you have shared with us earlier is based on one of our open source document viewer applications which is now obsolete and not supported anymore. We recommend you to please try our latest open source applications (listed below) that are rendering your provided tiff file perfectly.