I have had this problem and I was told that there is not yet a plugin for SU that works with E+ Ep 8.4 or 8.5. What I do is to create the model in E+ and then open in SU just to check geometry, but do not save it in su as idf. But my projects are smaller than yours.

I have had this problem and I was told that there is not yet no a plugin for SU that works with Ep 8.4 or 8.5.