Here are the steps to reproduce:

1. Create 100 page with the following:

   <ac:structured-macro ac:name="unmigrated-inline-wiki-markup">
     <ac:parameter ac:name="atlassian-macro-output-type">BLOCK</ac:parameter>
     <ac:plain-text-body><![CDATA[{live-template:FICHE-GLOSSAIRE}]]></ac:plain-text-body>
   </ac:structured-macro>
   

2. Goto the page "<Confluence BaseURL>/admin/unmigratedcontent.action"
3. The number of page is 100.
4. With the debug log enable with the package "com.atlassian.confluence.content.render.xhtml.migration" only the first 10 page in the search output was included in the migration list.