I strongly suspect your purebred Blue Ameraucana is not purebred, especially with bleed-through. Did you get his directly from Wayne Meredith? If someone other than Wayne Meredith did the breeding, then Wayne Meredith is not responsible.
Is he a Blue Ameraucana or is he a Blue Wheaten. That’s another possible explanation, maybe a likely explanation. But that still leaves questions.
I don’t know the genetics of a brown leghorn but a Blue Ameraucana should be based on extended black. That black should overpower whatever the leghorn is based on so you should be getting about half blue and half black chicks if both are purebred.
I don’t know what you will get with a Blue Wheaten Ameraucana over a Brown Leghorn hen, but again if both are purebred, the chicks should look a whole lot alike. Since the chicks look that different at least one of the parents is not purebred. Or another chicken is a parent.
The Pea comb is incompletely dominant over the single comb. That means you will probably not get a pure pea comb but you will see the effects of the pea comb gene. If you are getting single combed chicks then the Ameraucana is not pure.
There is a 97% chance that the pea comb and blue egg gene will be passed down together because of how close they are on the chromosome. But that is only if the parent with the blue egg gene and pea comb gene has only one of each and they are linked to start with. A pure Ameraucana is pure for the pea comb and the blue egg gene. In any case he will pass down one of each of those genes to his offspring since he does not have any others to give. You are getting single combed chicks. The father is not pure for the pea comb.
The pea comb gene, the blue egg shell gene, and the blue/black/splash gene are not sex linked at all. You cannot use any of those to determine sex.
Some leg color genes are sex linked. I can’t remember which colors those are. But you have to have the parents set up a specific way for that to work and they have to be pure for that gene. Since you are getting single combed chicks the father is not pure but a mix. Who knows what leg color genes he has? They are likely to not be pure. I would not count on leg color to give sex at all.
A brown leghorn cannot be used to make a red sex link or a black sex link. She just does not have the genes.