torch topclass example does not converge

[vlimant]

with

mpirun -tag-output -n 5 python3 MPIDriver.py topclass_torch_arch.torch train_topclass.list test_topclass.list --loss categorical_crossentropy --epochs 10 --torch --features-name Images --labels-name Labels

it gets no sensible loss values

[1,0]:loss: -506.394
[1,0]:acc: 0.333