Attachment missing in confluence pages

Note: If you are using version 5.8.16 or 5.8.17, or have used those versions in the past without running a script to fix the affected files, then you are likely affected by CONF-39975. Please see that ticket instead.

We found out that some of our Confluence pages have "unknown attachments". There are multiple pages that shows "unknown attachments".
Here are some details:

• Attachment images are still there and can be viewed in some pages, but some other page attachments are gone and also not visible in the page.
• This is not true for all. Some pages have no attachment images at all, but the images are visible with in the page.
• Workaround is to re-add the attachment image to the macro but since we don't know how many pages are effected, it would be better if there is a fix to apply.
• We are not sure if it is caused by moving pages within or another space, but this issue is now found in many other spaces.

Confluence version: 5.4.4

Note This issue was resolved in favour of CONF-41067, which has much more clarity. Please follow that issue after reading the description if you still think this affects you.