Do you have a screenshot of the issue?
Viewing post in [CGMZ][Alpha] Controls Window for RPG Maker MZ comments
To use the plugin command to add an actor manually, you will create an event, then double click in the Contents section to add an event command. On page 3, at the bottom right, there is the option "Plugin Command" which you will click. In the Plugin Name, choose CGMZ_Encyclopedia, in the Command Name, choose Discover Actor, in the id field, choose the actor you would like to discover in the encyclopedia.