Solved by tom in post #3 
              
              
                As far as I can tell, we have tensor[index] and tensor.index({index}) as indexing with a single tensor in PyTorch. 
Edit: In the 1.8.0 release notes, your case is in the backward compatibility notes here (from PR Making ops c10-full: list of optional tensors by smessmer · Pull Request #49138 · pytor…