Ok – so you have two instances of Undulator in a chain, one after the other? Can you provide screenshots or presets of the settings you are using?

Undulator has some internal dynamics control for creating swelling sounds, it's possible that this isn't being properly triggered.

No, i don't run two instances of Undulator in a chain. When i want to add Undulator to a 2nd and completely unconnected to the first midi track as an effect it either does not respond at all, or responds intermittently on being manually triggered. It never responds how one would expect it to. 

Please send a test session exemplifying the issue to support@eventide.com, referencing this post, and we'll look into the issue for you.