I have tried adding with the following widgets in SiteOrigin Page Builder: wp text, custom html, SO editor – and I get the same result. I enter code, update page, view online and all is good. Go back to the page and select the widget to edit, and SO Page Builder crashes with a blank page displaying the time (image below). It is impossible to re-edit the widget with the iframe. I can edit all other widgets. I can delete the iframe widget.
I have tried to reproduce the same error with SiteOrigin Vantage theme and all works ok, so I’m assuming that it is related to Ultra theme. Also, I use SO premium.
The date outputting when you open a widget is a common sign that Wordfence, for whatever reason, has incorrectly flagged the request. To resolve this please navigate to WP Admin > Wordfence Tools and open the Live Traffic tab. Filter by Blocked by Firewall and search the request you just made, it’ll be associated with your user account and the parm will start with body: instance=%7B%22frames%22%3A%5B%7B%22content. Click Whitelist param from Firewall.