I downloaded Page Builder from your site yesterday in the morning and built some pages with it without any problems. Later on I saw that there was an update to 1.4.4 and I updated it. After that I couldn't properly create new pages with Page Builder, they are just blank after editing. Also when I try to edit previously working pages built with Page Builder, they also get deleted/blanked.
To add some more complexity to the bug: Sometimes the inserted text is modified in some weird way (e.g. there are suddenly "/n" strings in the text and some HTML tags are missing).
Hope you can fix this soon, I really like your plugin.