Summary:

copy a page with linked attachment to another space will break the attachment link

Steps to Reproduce

1. Create a page, insert an attachement (attachment1.jpg)
2. Create a new page within the same space
3. Insert a link of the attachement by:
   • Click Insert more content
   • Files and Images
   • Search on other pages > Search for the attachment >(write "attachment1 on the field) Search > Choose the image > Insert
   • Save Page
4. Move this page to other space by:
   • Tools
   • Copy
   • Set New Location to new space and parent page
5. Save

Expected Results

Page copied normally with the attachment link still intact.

Actual Results

The image link has broken.

Workaround

Copy to somewhere in same space then move to new location in new space:

• Tools
• Copy
• Save to a temporary location within same space
• Tools
• Move
• Set New Location to new space and new parent page

Notes

Upon investigating, it seems like there is a difference of macro defined to link attachemnet from the same space and from different space
Storage format of page containing attachment from the same space:

<p><ac:image><ri:attachment ri:filename="connie.PNG"><ri:page ri:content-title="Confluence" /></ri:attachment></ac:image></p>

Storage format of page containing attachment from different space:

<p><ac:image ac:height="250"><ri:attachment ri:filename="connie.PNG"><ri:page ri:content-title="Confluence" ri:space-key="T5S" /></ri:attachment></ac:image></p>

(note the "space-key")

For more information please check the screencast attached