It appears the Excel Web Access web part is buggy within 2013's publishing layout pages. I have an Excel spreadsheet with multiple tabs that was displaying fine within both SharePoint 2007 and 2010. Similarly, it works as expected with an Excel Web Access
web part added to a team layout page in 2013. However, when I attempt to display it within an Excel Web Access web part on any of the publishing layout pages within 2013, it appears 'blank' (see image below). The behavior does not seem to have any corresponding
errors in either the server event log or ULS logs.
The problem seems to originate with SharePoint 2013's inability to elegantly handle an Excel workbook with only select items published to Excel services. In the team page layouts, the web part seems to detect such a scenario and display a drop down of views
containing each tab/worksheet title rather than showing all tabs at once. Since the same web part on the publishing page layouts does not seem to possess similar intelligent behavior, you can get around the issue by publishing all workbook items to Excel services:
- Open the document in the Excel desktop application
- Select File > Save&Send > Save to SharePoint > Publish Options > Show - Entire Workbook
- Re-publish or Re-save/Re-upload the Document to SharePoint
Once I did that, it displayed fine within either a publishing page layout or team page layout Excel Web Access web part. Hopefully this issue will be addressed in an upcoming service pack...