Bug misi level up

Hello Developer, I want to tell my complaint, so I want to report a bug on the FC Mobile mission,Namely the mission that we have to raise the 5 players we have to level 20, I have done all of that but the mission is not resolved whether this is a bug or I am the wrong understanding About the mission? If it's a bug, please fix it, if I'm wrong, please tell me how to complete the mission.