same issue here. Did you receive more information?
Can you provide us with more info on how you published your site? Provide a step by step procedure so that we can reproduce the issue at our end.
I've followed the step as you wrote in help part... right now I've created a subdomain for the web site and try it with in browser editing and it does work with the subdomain
This issue is been faced by few more users and the IBE team is investigating on this with the collaboration of Muse engineering team.
I suggest you open up a ticket with them directly here - https://feedback.inbrowserediting.com/#contact-us and wait for their response.
Please provide the further details which they might require from you.