Excerpt Macro null when including an excerpt from the same page

When using the Excerpt Macro to include another Excerpt, it only works if an Excerpt from another page is included.
If we try to include an excerpt from the same page, the following error is shown on the page:

Error rendering macro 'excerpt-include' : null

Steps to reproduce:

1. Create a new page on Confluence
2. Include the Excerpt Macro and write something inside it
3. Save the page
4. Create another page
5. Include the Excerpt Macro and write something inside it
6. Save the page
7. Edit the same page again
8. Include the Excerpt Include Macro, selecting the first page you've created
9. Include another Excerpt Include Macro, selecting the same page you are editing now
10. Save the page
11. Access the page and see the error