I'm now thinking it's something to do with the library templates you get with Adobe Encore.
That is not likely, but something is going on.
So what worked is export frokm FCPX as what? (Original means what? Does FCPX use the ProRes intermediate or what?) Imported to Premiere and dynamic linked to Encore?
What are your Encore project settings? And what transcode settings for the asset?
You might want to post a screenshot of our flowchart where you added the menu.