Hi,
For indexing, you don’t need lists, so you can remove the tolist().
The problem here is that you set multiple values at once and so there is a race condition and only one of them is set at the end.
You should use index_put_() 6 with accumulate=True to get what you want:
regular_tensor.index_put_((indices[0], indices[1]), values, accumulate=True)