diff --git a/lerobot/common/datasets/abstract.py b/lerobot/common/datasets/abstract.py
index 5db9de86..1e67e9d8 100644
--- a/lerobot/common/datasets/abstract.py
+++ b/lerobot/common/datasets/abstract.py
@@ -54,7 +54,7 @@ class AbstractExperienceReplay(TensorDictReplayBuffer):
         return {
             ("observation", "state"): "b c -> 1 c",
             ("observation", "image"): "b c h w -> 1 c 1 1",
-            "action": "b c -> 1 c",
+            ("action",): "b c -> 1 c",
         }
 
     @property
@@ -73,8 +73,12 @@ class AbstractExperienceReplay(TensorDictReplayBuffer):
     def num_episodes(self) -> int:
         return len(self._storage._storage["episode"].unique())
 
+    @property
+    def transform(self):
+        return self._transform
+
     def set_transform(self, transform):
-        self.transform = transform
+        self._transform = transform
 
     def compute_or_load_stats(self, num_batch=100, batch_size=32) -> TensorDict:
         stats_path = self.data_dir / "stats.pth"
diff --git a/lerobot/common/datasets/aloha.py b/lerobot/common/datasets/aloha.py
index f9351e20..afc28b1c 100644
--- a/lerobot/common/datasets/aloha.py
+++ b/lerobot/common/datasets/aloha.py
@@ -114,7 +114,7 @@ class AlohaExperienceReplay(AbstractExperienceReplay):
     def stats_patterns(self) -> dict:
         d = {
             ("observation", "state"): "b c -> 1 c",
-            "action": "b c -> 1 c",
+            ("action",): "b c -> 1 c",
         }
         for cam in CAMERAS[self.dataset_id]:
             d[("observation", "image", cam)] = "b c h w -> 1 c 1 1"
diff --git a/lerobot/common/datasets/factory.py b/lerobot/common/datasets/factory.py
index 5bb4b14f..29f40bc6 100644
--- a/lerobot/common/datasets/factory.py
+++ b/lerobot/common/datasets/factory.py
@@ -87,9 +87,11 @@ def make_offline_buffer(
     if normalize:
         # TODO(rcadene): make normalization strategy configurable between mean_std, min_max, manual_min_max, min_max_from_spec
         stats = offline_buffer.compute_or_load_stats()
+
+        # we only normalize the state and action, since the images are usually normalized inside the model for now (except for tdmpc: see the following)
         in_keys = [("observation", "state"), ("action")]
 
-        if cfg.policy == "tdmpc":
+        if cfg.policy.name == "tdmpc":
             for key in offline_buffer.image_keys:
                 # TODO(rcadene): imagenet normalization is applied inside diffusion policy, but no normalization inside tdmpc
                 in_keys.append(key)
@@ -97,7 +99,7 @@ def make_offline_buffer(
                 in_keys.append(("next", *key))
             in_keys.append(("next", "observation", "state"))
 
-        if cfg.policy == "diffusion" and cfg.env.name == "pusht":
+        if cfg.policy.name == "diffusion" and cfg.env.name == "pusht":
             # TODO(rcadene): we overwrite stats to have the same as pretrained model, but we should remove this
             stats["observation", "state", "min"] = torch.tensor([13.456424, 32.938293], dtype=torch.float32)
             stats["observation", "state", "max"] = torch.tensor([496.14618, 510.9579], dtype=torch.float32)
diff --git a/lerobot/scripts/eval.py b/lerobot/scripts/eval.py
index c9338dca..6435310a 100644
--- a/lerobot/scripts/eval.py
+++ b/lerobot/scripts/eval.py
@@ -126,7 +126,7 @@ def eval(cfg: dict, out_dir=None):
     offline_buffer = make_offline_buffer(cfg)
 
     logging.info("make_env")
-    env = make_env(cfg, transform=offline_buffer._transform)
+    env = make_env(cfg, transform=offline_buffer.transform)
 
     if cfg.policy.pretrained_model_path:
         policy = make_policy(cfg)
diff --git a/lerobot/scripts/train.py b/lerobot/scripts/train.py
index be3bef8b..f4b22604 100644
--- a/lerobot/scripts/train.py
+++ b/lerobot/scripts/train.py
@@ -142,11 +142,11 @@ def train(cfg: dict, out_dir=None, job_name=None):
         online_buffer = TensorDictReplayBuffer(
             storage=LazyMemmapStorage(100_000),
             sampler=online_sampler,
-            transform=offline_buffer._transform,
+            transform=offline_buffer.transform,
         )
 
     logging.info("make_env")
-    env = make_env(cfg, transform=offline_buffer._transform)
+    env = make_env(cfg, transform=offline_buffer.transform)
 
     logging.info("make_policy")
     policy = make_policy(cfg)