I haven’t got any answer yet, but I am just doing some testing and found out that if I added a new line on line 323 in “inc/Template_Handler.php” (after the echo of this code):
echo "<script></script>";
Then the line you mentioned above and the one I added here are printed out. But it doesn’t work if it prints out any other html-tag. This is quite a weird bug.
Automattic says that they can’t help us with third-party plugins, so we are currently in a difficult situation.
I have a question, as I’m quite of a nerd. I have done a little digging. Should window.scoInitializeInjectedInstances() be called at any point in time? If I call this manually in the terminal, the window.scoApi becomes avalible and the iframe loads.
There was one, have deavtivated it now without any change. This is hosted on wordpress.com, might that have anything to say?