Thanks for using GroupDocs.Viewer for .NET. Would you please share with us the browsers’ name and their version numbers as well? Furthermore, if you are using any of the Showcase applications, please mention its name. We look forward to hearing from you.
We are using New Front End
S7 Chrome 6.2.01.12
I phone 10.3.3
Thanks for providing the details. We tried to render you provided Excel document with GroupDocs.Viewer for .NET and the resultant HTML page has no issues (see output). It confirms that the issue is not related to the back-end GroupDocs.Viewer API and it occurs when the HTML page is displayed in the front end application. We also tested to view the problematic document in New Front End application but could not reproduce the issue at our end, and following are the results.
Are you able to see the sheets since in the images they are not displayed?