成唯識論演祕 3.12

3.12

謂無性人現行第七，熏成種時雖果俱有，以種子果體性沈隱，所以現七不名種子。

This means that for icchantikas (those lacking the [Buddha-]nature), when the active seventh consciousness perfidiously produces seeds, although cause and effect are simultaneous, because the nature of the seed-fruit is submerged and hidden, the active seventh is not called a seed.