Does anyone know why this would work:

=SUMPRODUCT((Log!$I$2:$I$9995=B8)*(Log!$J$2:$J$9995="Yes")*(TEXT(Log!$D$2:$D$9995,"mmm")=$C$4))
Yet this would not:

=SUMPRODUCT((Log!$I$2:$I$9999=B7)*(Log!$J$2:$J$9999="Yes")*(TEXT(Log!$D$2:$D$9999,"mmm")=$C$4)*(TEXT(Log!$D$2:$D$9999,"yyyy")=$D$4))