I'm having issues counting cells with a value of 0. The cells that I'm
counting are being filled by another function, but will always be a number.
When counting the cells that are <0 it works fine, but when I try it with 0
it is counting the cells no matter what is in them (negative number, blank,
text). What is wrong?

Here is the one for the <0 that is working fine:

=SUMPRODUCT(--(MOD(ROW(R6:R243),3)=0),--(R6:R243<0))

And this is the one I can't seem to get to work:

=SUMPRODUCT(--(MOD(ROW(R6:R243),3)=0),--(R6:R2430))