May be a bit late but I had the same issue and was able to solve it.
The reason of this is that you don't configured the correct IP address on the server before UCCx installation. The installer then populates the wrong information in the registry. The Agent Desktop then boots and fetches the wrong LDAP server IP address and is not able to connect. This is undocumented but I found out using the registry editor.
On the UCCx server, open up regedit and go to:
Search for those two keys:
IOR Hostname and LDAP Host 1.
Change the IP address to the correct IP address and reboot the server.
Then re-run the postinstall executable on the client in the Agent Desktop installation folder.
I did it like this and it fixed my problems.
You'll probably have the same issue if you change the IP address of the UCCx server.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...