Trying to A/B test the CTA on a Sign Up Overlay

[targetuser627]

I have a sign up overlay on my site that appears after 5 seconds of the user being on the site. 

I am trying to test a different CTA and I am having issues. 

It is working fine in the composer, but the changes are not appearing in the QA links. 

Is this something that would require custom code?

This is the error I am seeing "Action could not be applied due to missing or invalid mbox name"