You are facing a big problem, or a big opportunity. You realise that the most important thing about it isn’t its size. It is that it is different from the things you normally deal with.
It may seem familiar, like something you have dealt with before. But it hasn’t responded to the methods you used before, even if you have tried several times.
You may not be able to get agreement on how to approach it. You may be getting more and more frustrated that different members of your team can look at the same facts and come up with completely different views about what to do. Maybe everyone is blaming everyone else, instead of constructively approaching the challenge.
Or maybe you are making some progress, but realise that it won’t be enough. At the current rate you don’t have enough time, money or energy to do what you need to do in the time you have. You need a different approach.