Strange behaviour while performing retopology in Retopoflow

Lifelover

So I’m trying to retopo a hand with Retopoflow, which I’ll mirror across the X axis once I’m done. However, when I enter Retopoflow’s room, it instantly adds the mirror modifier and thus creates problems while performing retopology.

Symmetry is turned off, by the way. In essence, is there any way to work in asymmetry with Retopoflow?