The font style automatically changes in the Viewable Rendition in Vault. The source document has one font style and when the document is uploaded into Vault the font style changes to a different font style in the Viewable Rendition.
The document is replacing the font incorrectly. This is due to having an option to automatically update the template on the document turned on and the option to Automatically update document styles selected on the document (This is a default MS Word behavior):
To navigate to this setting on the source document follow the below bread-crumb trail:
File --> Options --> Add-ins --> Manage --> Templates --> Go --> Templates
By unchecking the Automatically update document styles option, the user can render the document without issue. Also, the font style in the Viewable Rendition will match the font style in the source document.
Vault Rendering Documentation: