Have you tried to make the join separately:
LOAD *, 'Displaced' as Trackin_Status;
SQL select uname;
Store Table _1;
SQL select distinct uitemno from rep ............... and A. uitemno = B.uitemno);
load * from Table_1;
load * from Table_2;
I hope this would be useful
Since you have the error message "Invalid object name 'REPTABLE_MDM' ", I assume that this table does not exist in the default library of the ODBC. So, you have the wrong library in your ODBC connection.
If you add the library to your SELECT statement, i.e.
SQL SELECT ... FROM <Library>.REPTABLE_MDM
it should probably work.