Missions are not available!

At the start of each day you are required to choose (depending on how much crystal you have) 3 missions in which you need only complete 1 to get a bonus. One of the missions I chose today was a battle. At least I thought it was a battle. I've searched wide and far and I can't locate it. Is there some place else to look? Is it possible it might be a tournament? Any help will be much appreciated. Thank you in advance.