Why does my gearbox model not reach a steady-state torque

I setup a 3 DOF two-stage gearbox model in Simulink as follows:

Even though I'm applying a constant input torque and a quadratic load on the output, the model isn't reaching a steady-state value where the aero load (multiplied by kF) is equal to the output load.

Any help or advice on why this is the case?

Many thanks,

Christo