I forgot a debugger statement in the DFFS_frontend_min.js file in v4.4.4.11 posted yesterday. If you have installed this version you must update the file /SPJS/DFFS/js/DFFS_frontend_min.js to fix this issue.
Unfortunately Microsoft have removed the scripting capability from the default templates in SharePoint Online, and this makes using Dynamic Forms for SharePoint impossible in these sites.
To have a modern site which scripting capabilities you must pick this template:
Using the Modern Content Editor Web Part will unfortunately not let you use DFFS in the NO SCRIPT templates.