Unable to link an attachment in the WYSIWYG Editor when from another page

I edit a page Space1.P in WYSIWYG editor. There is also a page Space2.WebHome which contains an attachment A.

In the WYSIWYG editor, I click the "Link" button then "Attached Files" and go for the "All pages" tab. I'm looking for the Space2 space but when I click on it, it doesn't show a list of available pages (there is other pages than WebHome on this space). Therefore, I'm not able to create a link with the attachment A.