Perhaps you could post a sample rvt and updated dyn and perhaps that will help us work out what’s wrong?
There’s a method for getting and setting the viewport centre… http://www.revitapidocs.com/2019/71734b96-6582-e6c5-674a-e6c092ced0f2.htm the node probably uses those.
Just wondering if your files maybe have different origins? Whether that could affect it?
Some discussion here might be relevant… Views Position on Sheets with Scope Boxes