Hi,
yes, front-end editor works fine.
Backend does not save changes in pages that have been once saved. You can create a new one and configure it to the fullest. But once saved, your cannot save any other changes. So you need to export it, create new page import the setting and continue the work...(as a work around) but pretty annoying...
Now I tried to update Page Builder to 3.8.2 to see, if there is any change, but Joomla! installation from local computer says it exceeds default max. size 2MB... I need to look up the setting, if there is a way to increase this size... maybe it is server setting, maybe Joomla! 4, have no clue...