Finally, someone sees what I'm trying to get at.

I'm not, however, saying that it is absolutely recessive or absolutely dominant, just that it cannot be an allele.

Even through crossing over during Meiosis the alleles would not end up on the same strand of DNA, however if they were on different loci on the same chromosome then they could end up on the same one leaving it open that neither would pass to the offspring or both would pass to it. Thus there may have been a platty daddy gamete that just never met with an egg. Still there are a lot of other things to consider before jumping to crossing over as being the reason.