I have about 38 domains mapped with domain mapping plugin v220.127.116.11 installed and just updated to Wordpress 4.1. I can no longer add domains. If I go to a site, then tools, and add a domain I get a spinner for about a second and then nothing happens and I'm back to the form. I've tried this on multiple different subsites with different domains and same result. Nothing. In my network settings I have verify DNS settings to off.