The function code fix does NOT solve the original posters problem – the issue with tinyMCE editor always switching to Text mode and adding images getting all wonky.
I am having the same issue with ACF and Visual Composer. As there is no apparent solution, I found an alternative solution – http://customfieldsuite.com/
I just installed the plugin and it is not causing any issues that I can tell with VC, although I haven’t dug into the functionality.
I don’t know if it’s poor form to post a different plugin here but if the developer isn’t looking into the problem we need a solution and this may be it.
