The Files Preview does not preview some excel files fully

Summary

When using the Files Macro to insert Timeline chart.xlsx, the preview generated is incorrect. The File Macro display the spreadsheet based on the page size set in the excel file. As an example, if the page size is set to A4, the File Macro will split the content to next page if the content exceeds the A4 page size. 

Steps to Reproduce

1. Download and attach Timeline chart.xlsx to a page in Confluence
2. Save the Page

Expected Results:

The table should look similar to how it does in Excel:

Actual Results

After the graph, further content is not shown:

Workaround

Some spreadsheets render more fully if viewed from the View link on the list of attachments:
To get to the attachment list:

1. Go to the page with the attachments and click the three dots next to Watch at the top right.
2. From the pulldown, choose attachments.
3. There is a blue link for "view" next to the spreadsheet.