Export to DWG gets line style scale messed up


I'm on Openbuildings update 6 and are trying to export drwaings to DWG.

I have a house with 6 floors. I've split the design files to 6 different files, one for each floor. But referenced them together in a composition file from where the callouts are taken. Each callout is then placed in a separate drawing file. All of these drawing files have the same scale. But when exporting them to DWG, the line style scale differs. This happens every time, and have happened many times before, in different projects. The pattern scale is the same and I use the same DWG-settings file for all exports. 

Why are they different and how do I solve this extremely frustrating problem.