Hello @alonmg,
Thanks for updating the thread.
I can confirm that Pro editor was not loading and gave misconfigured URL error message. This seems to be a a plugin conflict issue. I cleared cache and then deactivated all plugins and Pro editor seems to be working fine. I also created a test post in private mode and added couple of elements into that and every thing seems to be working fine. Please see following screencast.

I suggest you to deactivate all plugins and then re-activate one at a time to narrow down.
Thanks.