New realtime session does not synchronize with an existing editing session

Have XWiki Jetty/HSQLDB 18.9.0 with the experimental BlockNote editor installed. Configure BlockNote as the default editor.

Steps to reproduce

1. Start modifying alone any test page during realtime session
2. Add a new content or change the structure
3. Start another realtime session for another page

Actual result

When a user starts a new realtime editing session on a page that is already being edited in another session, the new session displays its own page content instead of synchronizing with the content from the existing session.

Expected result

The user starting the realtime editing session should see the current content from the existing session.