Thank you for the help. Component control was good. I can't believe I never knew about that mesh display feature but it proved indeed part only had fluid mesh.
Got it working but not sure of the specific issue/cause. For future reference I again re-imported part, ran diagnostics, ran feature recognition (never had to do this for FLOW and especially since it's only a cover that prohibits air flow), simplified by removing some internal features, and used a slightly refined local mesh on part itself. Used to occasionally have similar issues with 2017 but this is a first with 2018.