Good idea, I tried using .isnan().any() prior to posting the thread, since an error is never actually thrown. And nothing anomalous was found in the input data.
But maybe it is also needed to look at the gradients… difficult problem 

your input of a BatchNorm1D should be (N,C, L) and not (N,L) which is your case.

That’s true. Do you know if this is the case for ReLU aswell? Preferably I wouldn’t need any of them (norm and ReLU), I simply added them to try to mitigate this very problem.