So, if you've read divergent, you know that Tris had to face her fears and the leaders got to see them. But even though she was terrified that they would find out she was divergent, so why wasn't that an eighth fear?

We think (we being me and GOATY_POTTER ) that it's because 'the divergent' can resist and be aware during simulations, the simulation couldn't detect that fear, as part of Tris's divergence.