Exception: unknown storage type: -1

I’m working on utilising a custom loss function and op, but get the following error. Has anyone recieved this before and has any idea on the potential cause?

Error in CustomOp.backward: Traceback (most recent call last):
  File "/mxnet/operator.py", line 1029, in backward_entry
  File "/mxnet/ndarray/sparse.py", line 1185, in _ndarray_cls
    raise Exception("unknown storage type: %s"%stype)
Exception: unknown storage type: -1


Same problem here. Any idea of why?

Can you share your code @allenovo ?