Based on the responses so far, it appears the results are entirely consistent with random chance.
Couples who report no match on the compatibility lists outnumber the compatible/incompatible couples 2 to 1. Given that each sign lists a maximum of five other signs to consider and ignores half of the total number of signs, this is no surprise.
Of couples who report a mutual (in)compatibility, those who say they are compatible with their mate outnumber the incompatibles, again 2 for 1. Again, this is to be expected, because each sign lists three compatible signs but only one or two incompatible signs.