What would cause the session ID to be lost

Problem:

          In assembly relations a dimension session ID is lost/changed.

Information:

          The error given in the message line is "Line 819 assembly RAKE_BEAM: Symbol 'D0:14826' not found."

          The error given in the relation editor is "Invalid symbol 'D0:14826' found.

          For example D0:124=length:199  will change to  D0:14826=length:199 

          The part that the relation is referring to is suppressed by pro/program.

          I can fix this by opening and regenerating the suppressed part. Then when I go back to the assembly the relations are fine.

          This is not happening to any other suppressed parts within that same assembly.

What do think is going on here?