Attachment Selector macro doesn't upload files when save mode is form (default)

Put this in a wiki page:

{{attachmentSelector classname="XWiki.XWikiUsers" property="avatar"/}}

Then edit that page in Inline Form edit mode in order to get the "Choose an attachment" button. Click on that button, then on "Browse" and select a file to upload. Finally, click on "Upload and select" button. This closes the attachment selector. Open it again and notice that the file you previously "uploaded and selected" is not listed.