IES recognizes internal partitions as exterior

[RHDHV]

Hello,

I have a problem exporting my sketchup model to IES.
The model exists of an office with an atrium and a central shaft containing toilets, elevators etc.

In sketchup rooms are defined correctly.
When I launch IES the shared wall between the atrium and the surrounding floors is shown as an internal partition.
But the shared wall between the central shaft and the office floor is shown as an exterior.

What am I doing wrong?