If a case contains automatically generated interfaces, and those interfaces were generated as a result of 'contact' information in the original cmdb file, it is possible that a subsequent import of a def file created from this set-up would lose this connection and the interface would then be missing from the set-up.
This is due to not all connection data of this type being written into the def file.
Use the cfx file, which has topological information correctly stored.
ANSYS CFX Release 12.0. Note that this fix only corrects the writing of new def files; it does not correct the import of old def files written by CFX-11.0.