I have a similar problem with the out of the box ITSM NLU for Virtual Agent NLU. But in my case it just says "Cannot convert null to an object." and will not let me Publish. I have had a HI ticket open for a very long time on this and they can't seem to figure it out. Nothing changed to this one except I did a recent update of the plugin. We have not modified the out of the box version, but we do use the intents in some of the topics we cloned to modify for our enviroment.