Domain Mapping site admin behaving strangely

I'm not sure if this is since the last update but the site level Domain Mapping admin page (Tools > Domain Mapping) started showing several oddities.

I tried disabling all other plugins both site level and network wide but no change. I tried disabling and enabling Domain Mapping but no change.

These are the things going wrong:

1. entering a domain pointing to another IP it is still marked as valid;
2. after adding a second domain, there is not that asterix to select one as primary;
3. after refreshing the page (!) the fields "Connect Domain" and "Front end redirect should be" are gone;

What is going on?