IntelliJ Unable to Add Language

I've created a language that is not based on baseLanguage (it outputs XML instead).  I've created the IntelliJ plugin for it correctly and the plugin installs fine alongside the MPS plugins in 2017.3 version, but I cannot seem to add the language to an empty (non-Java) model in order for it to be used.  Are IntelliJ language plugins from MPS limited to baseLanguage children only?