Assume that you create a site by using the Visio Process Repository site template in Microsoft SharePoint Server 2010. You upgrade the site to Microsoft SharePoint Server 2013. In this situation, the Microsoft Visio 2013 document template (VSTX) is not available in the New Document list.
Note This issue only affects Visio Process Repository sites that are upgraded. The new SharePoint Server 2013 Visio Process Repository sites support both VST and VSTX document templates.
This is a known issue.
To work around this issue, manually add VSTX document templates to the Process Repository library.