This may not directly answer you question, but how do the instructions tell you to add the cinnamon? Dry hop style, tincture, boiling in water? I ask because ground cinnamon would be fine in certain applications, but not others.
If you wander over to Upstate Mike's caramel apple cider thread you'll get an idea of what some people's experience has been using ground cinnamon. In the original recipe you boiled ground cinnamon in the caramel mixture. However, boiling cinnamon causes it to form snot like tendrils after it is added to the cider. They don't taste bad, they just look horrible.
This snot is exactly why people started using cinnamon extract instead, or dry hopping with cinnamon sticks, tinctures, and a variety of other methods, just to avoid adding the cinnamon directly to the cider. You can get all the flavor with none if the snot!
If you're not boiling it you probably won't have this issue.