I am not sure if something changed with MZ 1.8 but I can't get this to work at all, even in a fresh project
I did not test it before moving to 1.8 unfortunately.
I set things up in a fresh project and made a simple common event that just displays a text box. The common event does not have any trigger.
When I set the plugin params I choose the common event and a button.
I have tested with various button configs in testplay battles as well as battle tests from the database. It does not seem to work regardless of what key I set it to. I have tried using both a controller and a keyboard.