The Rajagopal2015_TorsTib_l_Prox0Dist-30Deg.osim example is associated with some degrees of dorsiflexion in the ankle joint (the left forefoot is not in contact with the ground):

this is due to the ankle joint reference system (Y not aligned with torsion axis):

It can be fixed applying the same rotation to the RigidBodyXYZ vector of the ankle parent frame.
Thank you @mrrezaie for pointing this out!
Luca