My JEI shows a Brass Chicken with no breeding combo, and I can't seem to find Brass chicken listed in the config anywhere. Trying to collect all the chickens so just want to make sure this isn't a real one for the mods I have. Would that be an issue with Roost or with JEI?

I found the solution.
Check out the config file of morechickens. You can find it in /YourModpack/config/chickens/morechickens.json then search for Brass Chicken. In my case there was not parents so I added them.

I have the same problem. In the modpack Ragnamod V the craft is active. I tried to find a way to add a bredding recipe with crafttweaker but i didn't find anything.