The usage of the stimulus and the non-integrated variables don't work together.
The problem is that the size of the array of the stimulus is too big and it can't be added to the state variable in the integrator.
If I am correct, the problem is because the stimulus is defined with the number of state variables( +https://github.com/the-virtual-brain/tvb-root/blob/3e1315960c684bb5ba8a6903a46243f3acfe913f/scientific_library/tvb/simulator/simulator.py#L302+ ). It should be defined with only by the state which is integrated.
I propose to modify :
stimulus = numpy.zeros((self.model.nvar, self.number_of_nodes, 1))
stimulus = numpy.zeros((self.model._nintvar, self.number_of_nodes, 1))