Model incorrectly detected as linear for ramsey_model

I am experiencing trouble with ramsey_model in Ramsey_Example.mod. If I use stoch_simul via dynare Ramsey_Example -DOptimal_policy=0, then

M_.nonzero_hessian_eqs = [0 1 2 5 6 7 9 10 11];
M_.hessian_eq_zero = isempty(M_.nonzero_hessian_eqs);

but with ramsey_model via dynare Ramsey_Example

M_.nonzero_hessian_eqs = [];
M_.hessian_eq_zero = isempty(M_.nonzero_hessian_eqs);

So for some reason the model is detected as being linear, which it is not