Yep! Now it makes sence why its not exporting MDSYS. I did try to export user CTXSYS on v817, I got the same error. Other dba who works on Spatial objects says:

MDSYS Doesn't own any users data except the metadata, prebuilt functions for geometrical/spatial objects. That means MDSYS data is static and never change from the installation time. When you install the dataabse by default MDSYS will be installed and it will always be there and exp utility discard that user for exports as there is no need. After the import MDSYS can manage user spatial objects the way it is managing on the prv database. Same case with CTXSYS too...

Makes sence from what my dba saying now...