I've run into a number of CI's that give an error when trying to view the Map - "Unhandled system exception: An item with the same key has already been added. "
Additionally the Map Tree will not display upstream relationships I know are there.
Could this be a result of a relationship import mis-configuration (we recently did one , using a mapping that had not had any issues in the previous year plus).
Any clues as to the source of the error message? The CI Named Rel Link table has an index on Source, RElationship, Destination. It should not allow duplicates for those unique values.