if there is no problem with the Client to Server communication just try to set a new Password within the specific policys. There are options for locking the userinterface with a password and there is the option for locking any uninstall (via systemcontrol, software, uninstall) attempt with a password.
Nevertheless some more Informations could not harm.
Did you do an upgrade install - managed via ePO or SaaS/Cloud, checked for any known issues and incompatibilities before installing the Software? Which Intel products were installed before you did the install of ES10.x and with which ES Version did you encounter this?
We got one System which was like the one you described. We were not able to backtrack the cause but my guess is, there was a incompatibility which we did not evaluated until this one. At the end we did a clean install of the sytem and without changing anything within the ePO-Configuration everything went fine which underlines the possibility of an incompatibility on our side.
Moved to Endpoint Security 10.1
Did you checked with the default password: mcafee( all in lower case)