Map Models - Refererence disappear

Hi,

I have dgn file with one design model (Default) and several map models. All map models have default model referenced and all maps are properly shown UNTIL new reference of the same (Default) model is attached. Then my previous reference dissapears, usually not immediately but when I try to move reference. I noticed that when the drawing model and map models are in two different dgn files everything works fine so my question is - are map models designed to work with references that are not in the same design file as map models or it is a some kind of error in my PowerMap (version 08.11.07.86)?