Datamesh is working fine when a new row is inserted OR if the target field is empty.  However, in an instance when the target lookup value changes, it is not recognizing the change

In our example, Column A is the lookup value and column B is the cell we want updated.  When column B is empty, datamesh works fine and populates column B.  However, if we update the value in Column A, it should rerun and place a new value in column B.  It is not doing this even if we run the datamesh manually.

We can get it to work, but deleting the value in column B and then rerunning the mesh, but there is not a chance i can get our clients to do that consistently.  

Any thoughts would be appreciated.  First screen shot is target sheet.  Second screen shot is source sheet.  Third screen shot is datamesh setup