IFC files

I have received IFC files for other members of the design team. When i import the IFC file into AecoSIM i get different (and less acceptable) results than if i open it in AecoSIM. Why is this? Secondly is there any way around this? If i import i can get the family and parts and therefore cut sections and plans etc (apart from the missing elements that disappear when i import!) however if i open it i do not get any of this and therefore cant use the model in my drawings.