I think that the site lacks the feature to get a list of unsolved missions.
There is a list of solved missions: https://py.checkio.org/user/vinc/list/
Here are published solutions: Https://py.checkio.org/user/vinc/solutions/
But there are no unsolved missions as simple list.
To see them you have to go to the islands, find them, go back and so on.
Or I do not know how to get this list?