Superannuation Guarantee not calculating for the first employee only

Have just done payrun for week ending 31/07/2018.  The first employee hasn't got any superannuation guarantee calculated even though their weekly pay is the same as always.  Every other employee has super calculated and after checking their info there is no difference in details between employees.  I have not changed any superannuation preferences.  We have not encountered this problem before and it won't allow me to change the super amount from $0 to $131-02 manually.  As super is reported to the ATO via STP, I cannot lodge as yet as the super amount is incorrect.