In UCCX 10.0 Cisco decided to change the way UCCX works so that hostnames not IP addresses are used for inter-server communication. The UCCX Editor was also changed to use hostnames, resulting in the odd situation where you can authenticate against the UCCX server by IP address, but browsing the script repository or using reactive debugging doesn't work. This is because the UCCX Editor will try to use the hostname of the UCCX servers, if the DNS A records don't exist or you're connected via a VPN without correct DNS configuration then the DNS resolution will fail & these features won't work. The error message provided is pretty vague on this, for example if you try to use reactive debugging it will get stuck with the message "Engine hostname list is empty. Check the ldap for enabled unified ccx engines".
The solution is to kludge it by editing your local hosts file to contain the hostname & FQDN of the UCCX server(s). On Windows edit the file C:\Windows\System32\drivers\etc\hosts, example entries below: