This could be a known bug or simply me suffering from brainfreeze searching google came up with nothing relevant.

A simplified scenario that reproduces the problem, first copy the table below into A1:B4

A 1
A 2
B 1
B 3

Enter the formula =SUMPRODUCT(COUNTIFS($A$1:$A$4,"A",$B$1:$B$4,$B$1:$B$4))

Now go to formula evaluation and click evaluate once, the result, SUMPRODUCT({1,1,1,0})

Any thoughts why the third row is being counted when it doesn't meet the criteria in column A?

Thanks in advance.