Windex between shots is a good thing. And I never used that Citrus barrel blast, but I would guess that is some good stuff. Still, let me guess that the "ash" that you might be finding could be small fragments of bore butter. Bore Butter is a wax.

I really can not say for sure that the stuff your findingis bore butter. BUT as most people on the forum know, I am not a bore butter user and I do not endorse it in my muzzleloaders. Still my attitude with a lot of things is, your rifle, do as you like. Personally I would boil that bore butter out of the rifle and then use a quality gun oil to protect my rifle barrel. Good luck.