I had a mission "Large Plane Crash" at my airport. It had 18 patients. I sent all required units plus a couple extra and when it was supposedly finished it would not transport the last patient (was not asking for transport) I was able to utilize the "Finish mission by watching ad" (Available on mobile version, and I believe only one per day) to clear the mission. Quite frustrating. If the add option was not there then I would have had to spend coins. No one should have to spend coins to finish missions.
I apologize if this has been mentioned before I looked through the last couple pages of posts and did not see anything like my problem.