Hi, I have encountered this problem time (a lot of time) ago and honestly I didn’t know how was solved but, it was.
Anyway, now I am having the same problem, exactly same, as the guy in this topic:
https://www.8theme.com/topic/wp-bakery-plugin-does-not-allow-me-to-use-the-backend-editor/
meaning, I cannot access to the backend editor, I cannot edit neither the “screen options” since it won’t happened anything when I click on it. I can however access to the frontend editor BUT I can’t save any change I make.
I have the plugins up to date and also deactivated everything that wasn’t in this list: https://www.8theme.com/documentation/xstore/plugins/included-plugins/