In the presence of an external magnetic field (1.8T) applied horizontally along the shear-aligned direction of the active nematic within a cuboidal channel, flows perpendicular to the field are hindered (time<6 min). This suppression arises because the active stress that distorts the nematic alignment encounters resistance from nematic elasticity and the externally applied magnetic field. When the magnetic field is switched off (time>6 min) (indicated by spikes in PIV vector magnitude due to sample holder movement), the nematic undergoes a bend deformation, initiating flows perpendicular to the field direction. This observation suggests that the magnetic field's influence lies in aligning the liquid crystal rather than disrupting the active stress through interference with motor proteins.