Issue Summary

Visio diagram files (vsdx) are not being displayed/previewed when you click on view on the attachments of the page, or when you click to view the file uploaded in the page, like a PDF does. 
The .vsd file preview works, but the .vsdx does not.

Steps to Reproduce

1. Upload a .vsdx file on a Confluence page directly in the page or through the attachments on the page
2. After uploading, click on the file to preview it or go to the attachments of the page and click on view

Expected Results

Visio .vsdx files open the preview normally as the .vsd files.

Actual Results

It does not open, only downloads the file.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available