Any chance you looked at the Console.exe.config on the local client after upgrading them?
A couple things to look at:
1. Make sure you are pointing to the correct framework that is supposed to be used for your integrated logon. This is in the
<add key=TPS Host" value="http://ServerName/Instance.Framework" />
<add key="Url" value=http://ServerName/Instance.Framework / >
2. At the bottom of the config, check and make sure you are pointing your logonpolicy to integrated, rather than explicit:
<add key="LogonPolicy" value="Integrated" />
3. Verify the framework running in configuration centre has its Logon policy set to Integrated
We haven't tested 771 yet and are still on 7.5 SP1, but i could see those settings possibly being defaulted during an upgrade. Hope it works!