I don’t see anything obviously wrong.
I used the provided input shapes for the data and [64, 50] for the target.
However, the Keras code throws a shape mismatch error:
y_pred = y_pred.reshape(y_pred.shape[0]//self.opt.nCrops, self.opt.nCrops, y_pred.shape[1]);
ValueError: cannot reshape array of size 3200 into shape (6,10,50)

while this seems to work fine in your PyTorch implementation.