If you try to create a new domain interface, by duplicating an existing one and changing the locations to reflect the new locations, the new interface gets created and updated, but the corresponding boundary conditions in the fluid domain(s) are not created and do not get updated.
For each domain interface, there should be two corresponding boundary conditions contained within the domains settings. CFX-Pre is failing to create these when an interface is duplicated.
Create the domain interface from scratch.
ANSYS CFX 11.0 Update 1.