MAT seems to be very unstable right now.  I am working on developing the above mentioned measure.  Many definitions that have been created without errors are now showing errors.  If I resave the definition, it sometimes can be saved without errors.  However, then other definition that reference that definition indicate there is an error.  So when I go back to the definition again, it is showing there is an error.  In actuality, there is no error.  For a good example, look at the definition "Delivery Encounter Near Term".  This is used in a lot of definitions and repeatedly is showing there is an error but there really is not.