Cannot upload pictures when editing a section

Reproduction steps:

• Disable inplace editing by setting edit.document.inPlaceEditing.enabled = false in xwiki.properties
• Go in the Sandbox page and edit a section
• Upload a picture in the editor (using drag&drop for example)
• Save & view

Expected result:

• in the editor the upload is properly done, and when saving the image appears when viewing the page

Obtained result:

• in the editor the upload is properly done, however when saving the image does not appear. The console displays:

  2022-06-13 09:47:56,922 [qtp1577592551-111 - http://localhost:8080/xwiki/bin/download/Sandbox/WebHome/image-20220613094632-1.png] WARN  c.x.x.p.XWikiPluginManager     - downloadAttachment failed for plugin [image]: null 
  2022-06-13 09:47:56,922 [qtp1577592551-111 - http://localhost:8080/xwiki/bin/download/Sandbox/WebHome/image-20220613094632-1.png] WARN  c.x.x.p.XWikiPluginManager     - downloadAttachment failed for plugin [zipexplorer]: null