File Preview Bug in Confluence for .xlsm File Format

Summary

According to this comment in this bug report - CONF-24444, .xlsm file format is supported from Confluence 5.7 onwards. However, File Preview function breaks in the later version in Confluence.

Steps to Reproduce

1. Add a new Page in your Confluence instance.
2. Attach the sample.xlsm file to this page.
3. Try to preview the attached file in your Confluence instance.

Expected Results

Confluence will render the .xlsm file accordingly.

Actual Results

Nothing is rendered on File Preview attempt, Confluence will only allow user to download this document instead.