Hello Yann! I’m getting the same result, but this isn’t how you usually put tensors into your GPU’s VRAM anyway. If you wish to put R into the GPU memory, use R = torch.randn((5,5)).cuda() instead.
print(R.is_cuda) will then return True.
This: print(torch.tensor(torch.randn((5,5), device='cuda:0')).is_cuda) would also return true, but the outer tensor is redundant, so print(torch.randn((5,5), device='cuda:0').is_cuda) is equivalent.
I do believe you found a bug though, since print(torch.tensor([1,2,3],device='cuda:0').is_cuda) returns True.