Well, it's been several months, do you still have this problem? As you can see, people are not jumping up and down waving their arms to provide you with IFC workflow solutions! I am just starting to get into this myself, and while I am using AC10, I would be happy to try to duplicate your experience - import/export workflow...
Best,
Andy
Andy Thomson, M.Arch, OAA, MRAICDirector
Thomson Architecture, Inc.Instructor/Lecturer, Toronto Metropolitan University Faculty of Engineering & Architectural Science
AC26/iMacPro/MPB Silicon M2Pro