I was following the recipe on the back of the box, which says to boil 2 1/2 cups of water and 1 tsp salt, then to mix 1 1/4 cups of corn meal with 1 cup of cold water, then to add this mixture to the boiling water, stir frequently and cook for 5 minutes or longer until it is thick. The problem was, it was not thickening. In fact, it was thicker when I first added the corn meal to the boiling water and it got thinner as it cooked.

I was making this as part of a tamale pie recipe. That recipe gives similar instructions but says to cook for 30 minutes stirring regularly. In the past I've made it this way and it gets very thick and starts to stick to the pan after 30 minutes. In this case, it was very thin no matter how long I cooked it. (I tried it twice, once according to the directions in the tamale pie recipe and once according to the directions on the back of the box. In either case, the mixture was very thin and soupy, when in the past it's been so thick that it sticks to the pan).

The tamale pie recipe says to then pour the corn meal mixture over the tamale pie filling and bake at 375 for an hour (normally, the mixture is so thick by this point I have to use a spatula to spoon it over the pie filling. In this case, it was so soupy I could easily pour it over). Under normal circumstances, after baking, you will have a thick solid polenta "crust" over the pie filling. In this case, when I removed it from the oven, the polenta had completely dissolved and mixed with the pie filling so I ended up with a soup.

I've never encountered such a thing. My only guess is that something is wrong with the corn meal. I am going to try another brand today.