Using the wrong kind of yeast
With so many different types of yeast available, how do you choose the best one for your cinnamon rolls? To begin, you should distinguish between the various types of yeast used in cinnamon roll recipes. Active dry yeast (ADY) and instant yeast are the two most common types. Active dry yeast is powdered yeast that must be "bloomed" before being mixed into the dough. To bloom this yeast, combine the specified amount of yeast with warmed water or milk and granulated sugar and set aside for five minutes. The presence of a fruity odor in the cup indicates that the yeast is active, healthy, and ready to rise.
Instant yeast does not need to be mixed and can be added directly to the dough. For baking, use instant yeast because it rises the dough much faster than active dry yeast. This time difference is caused by the instant yeast's small particle size as well as the addition of accelerant agents in the instant yeast packets. Active dry yeast may still be an option if you plan to make overnight cinnamon rolls.