For me, Ni has to be allowed to work in the background. If I focus on trying to solve a problem, I just sit there, spinning my wheels, getting more and more frustrated, and more and more paralyzed, and unable to come up with any solution. When I find that happening, I find it best to put the problem aside, and best of all, to sleep on it. Almost invariably, in the morning, when I wake up, I have the solution in my head. Also, with focusing on Ni, I can get into an Fi-Ni loop, which you are probably familiar with.
I can't steer or control or guide my Ni--just let it do its thing out of sight. That's best, IMO. I wonder if Fi is the same for you?