Hi,
I think you need to specifically define the combination.



 mohamed_nabil:

torch.autograd.backward([loss_1,loss_2,loss_3])


For instance,
loss = loss_1 + loss_2 + loss_3
loss.backward()

I have never seen the approach you haved used to combine multiple losses so maybe the function you calling is not doing what you expected.
Bests,
Nik