Did some more testing. On a Pivot table this time. The PT headers cause a Value error when you multiply the first three arrays with H:H.
Include an IFERROR inside the SUMPRODUCT like this:
=SUMPRODUCT(IFERROR((A:A=M4)*(B:B=N2)*(C:C=N3)*H:H**,0)**)
As said earlier, SUMIFS doesn't have this problem.