FTR, temporary attachments were disabled for real-time editing by XWIKI-18810 with https://github.com/xwiki/xwiki-platform/commit/8feb6f5e4a532257177738ffdead28dd61d6b3f8#diff-c16357407f3d70c232d1c1352f3e89dc897ad0f81d5556ef2e85f7e6afc5bf37R256 .