Not sure if this helps, but I was trying to add a google verification code and getting constant failures in DNS settings. I then noticed you can access DNS setting from two different places.
If you are on your dashboard and click the domains tab at the top of the page right beside dashboard, nothing works. If you have an active website on your dashboard and you enter domains from that point of entry, select your domain and click edit DNS in the top right hand corner, everything seems to work fine, including no error message under adding presets. If you don't have an active site to leverage that point of entry to DNS, the other way is just not working.