Why are my dumplings made of evil?

Maybe you used too much evil, as in mistaking teaspoons of evil for tablespoons of evil? :^D

Seriously, the recipe itself could have errors like that, either from being handwritten in one of its iterations en route to you, or even a simple typo. Common ones that could produce what you describe are teaspoon vs. tablespoon, baking powder vs. baking soda, etc.

Did you taste the powdered mix dry? I'm not sure what it would taste like in that form, but I'm guessing a bland, flourish kind of non-flavor as opposed to the metallic taste your husband picked up.

Is it possible the bowl in which you mixed the dumpling batter had something in it? Like unrinsed soap that made it into all or just a few of the dumplings, or someone sprayed another cleaner, one not intended for food utensils, in the area of the bowl?

I use very few mixes or prepackaged food of any sort, as I absolutely love to cook and bake with fresh foods as much as possible. Chicken and Dumplings though is one thing I have been cooking for more than 30 years, and my family's absolutely most favorite of all my dishes. I use regular Bisquick (or Jiffy Mix, either one), and regular whole milk. Alternatively, during the winter when I don't get to the grocery store for a couple of months, I'll put about 2 teaspoons of dry milk powder into the center of the mix and then use water to make the dough. The soup or stew needs to have enough liquid to allow the dumplings to be resting in the liquid, or even mostly submerged (though not necessary). I let the meal simmer on low heat with the dumplings added, for about 3 minutes. Then I put the lid on the pot and continue to simmer at lowest heat for another 5 to 7 minutes (or until I see the dumplings are fully raised and cooked - or if you wish, test with a toothpick like you would a pie to make sure the center is done). When I serve the dish, I take some of the broth/gravy, and spoon it over the dumplings. In my opinion, so-called "low-fat" or "more healthy" is anything but "healthy". Remember, what they take out to make it "healthier", they add more chemicals in to make up for the loss.

EDIT:

I believe the odd taste was the combination of ingredients, the Heart Smart Bisquick w/ buttermilk. IMO, so-called low-fat or more healthy items are anything but "healthy". What is taken out to make items "healthier", chemicals are added in an attempt to make up for what was lost. I believe if whole milk and regular Bisquick or Jiffy Mix is used, the dumplings will come out wonderful. I posted my tips/recipe merely to perhaps help Yamikuronue to try and make them again

The metallic aftertaste is because the mix had a unbalanced baking soda to phosphate ratio. Whenever your finished cook product is either yellow or has a orange spotted tint within it you have a unbalanced mix. The phosphate must have something to react with. A unbalanced PH will cause the aftertaste. (Metalic =too basic)

I believe that this mix uses a combo phosphate ratio. (V-90 plus Active-8= Stabil 9) One phosphate reacts immediately with water and will rise 80%. The balance will rise when heat activates it. The second phosphate rises 20% with water and is a primarily a heat activated phosphate.

You must mix and wait a minimum of 30 minutes when using phosphate based mixes to permit the leavening to balance out. You should use cold water only.

Your dumplings taste bad because Bisquick tastes bad. No matter which variation you use, the stuff tastes horrible. I have been cooking for 40 years of married life and 10 years more under my Mother's tutelage. I can tell you precisely which item on a table has been made with Bisquick. And really, it is not hard to make dumplings, biscuits or cakes, using your own ingredients.