diff --git a/pina/label_tensor.py b/pina/label_tensor.py
index 4c30f4b56..644804424 100644
--- a/pina/label_tensor.py
+++ b/pina/label_tensor.py
@@ -448,6 +448,9 @@ def __getitem__(self, index):
 
         # Retrieve selected tensor and labels
         selected_tensor = super().__getitem__(index)
+        if not hasattr(self, "_labels"):
+            return selected_tensor
+
         original_labels = self._labels
         updated_labels = copy(original_labels)
 
diff --git a/pina/model/block/convolution_2d.py b/pina/model/block/convolution_2d.py
index 665ddafab..4c085338e 100644
--- a/pina/model/block/convolution_2d.py
+++ b/pina/model/block/convolution_2d.py
@@ -265,7 +265,7 @@ def _make_grid_transpose(self, X):
 
         """
         # initialize to all zeros
-        tmp = torch.zeros_like(X)
+        tmp = torch.zeros_like(X).as_subclass(torch.Tensor)
         tmp[..., :-1] = X[..., :-1]
 
         # save on tmp