I’ve been working on this project for a coulpe of weeks using the Dante theme and suddenly the page builder stopped working. I tried to activate it inside the post editing page and all I got was a message like Loading…, I checked the console and there was a TinyMCE warning and when i changed i received an error that it couldn’t save.
I then went to Google to try to find people having the same problem and all I found was a thread on their support but I couldn’t access because there was a problem with my client’s purchase code so we lost a couple of days trying to get access. Once we were in I found a few other threads and no solution from them. There was only one guy that found out the problem and I am sharing here because it would be easier to find and access.
You probably get this error because, like me, you entered text mode and then tried to activate page builder. You simply have to go to Visual Mode and then activate page builder!
Text Mode > Visual Mode > Page Builder
Not sure if this was related to a plugin, I saw some people saying it was ACF, but either way… Only activate Page Builder when in Visual Mode.