I have the same problem. In my case its the yeast. I wash my yeast and try ro get the most out of it. Pretty much after 3 months in the fridge without using it is about the life of my yeast before things go sour. I have been sticking to SO5 for now and no sour beers this far.[emoji2]
I sub grits for corn maze all the time but the is for cream of three crops type of beer. Im not sure how that plays into this recipe. Im not seeing that in this recipe.
If i remember correctly when i brewed this, it wasnt all that great till about month 6 for it to start to shine though. Could be the yeast hasn't settled yet and that is what your picking up in the flavor.