After simple and common user's actions:

1. Create page
2. In the creation dialog add attachment and insert viewxls macro for it
3. Save page
4. Edit page (ex. add a word at the end)

Activity stream macro will fail to find attached file after editing the page.

This KB article: Viewfile Macro is Unable to Locate the Attachment is useless here.

Now, more detailed steps:

1. Install clean Confluence (see Environment)
2. Create space TST
3. Rename page "TST Home" to "Home" (optional step)
4. Edit page Home - insert Activity Stream macro with default settings
5. Click Create button
6. Page name = XLS, add attachment ActivityStreamTest.xls and insert Office Excel macro with this attachment
7. Click Save button
8. It is OK here
   
   
9. Edit XLS page - add some text to the end. Save page. Here is the problem:
   
10. The page looks good:
    
11. BUT, if I go to the page's history and open first version of page, I'll see the same error:
    

UPD: Problem in Activity Stream still exists after deleting the XLS-file and reattaching it again.