Since the version of Revit 2012 (it seems to me) Autodesk has changed the Lookup Tables system.
Before, the Lookup Tables were in a directory.
Now the Lookup Tables are directly integrated into families.
This has the advantage that the Lookup Tables file always follows the family, but on the other hand it creates a disadvantage that if a Lookup Tables is used in several families and I want to modify this Lookup Tables, it must be reloaded in all families .
While with the old method, "Lookup Tables in a directory", if you modify a value of a Lookup Tables, all families are updated.
Autodesk should allow users the choice to use both solutions.
Perhaps with an option in the formula syntax of Lookup Tables.