Place corn husks in a bowl, cover with boiling water, and soak for 30 to 60 minutes. Drain, place on a work surface, and cover with a clean, damp towel.
While corn husks are soaking, combine masa dough, baking soda, and water in a bowl. Knead until dough has a smooth and even consistency, adding more water, 1 teaspoon at a time, as needed. Take care not to add too much water.
Beat butter, vegetable shortening, and sugar together in a second bowl with an electric mixer until smooth and creamy. Slowly add masa dough and knead until mixture has a uniform consistency. Mix in chopped pineapple.
Spread about 1 tablespoon masa mixture onto a corn husk. Fold the bottom of the husk over the filling, then fold sides of husk together, one over the other. Finally fold the top of the husk into the tamale, making a little package. Repeat with remaining husks.
Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to a boil, then reduce heat to medium low. Add tamales with the open side up and cook covered until filling is heated through and separates from the husk, about 1 hour.