diff --git a/src/lerobot/policies/factory.py b/src/lerobot/policies/factory.py
index 6bad1a4c22..b3b9b302bd 100644
--- a/src/lerobot/policies/factory.py
+++ b/src/lerobot/policies/factory.py
@@ -168,7 +168,7 @@ def make_pre_post_processors(
             config=policy_cfg, dataset_stats=kwargs.get("dataset_stats")
         )
 
-    elif isinstance(policy_cfg.type, ACTConfig):
+    elif isinstance(policy_cfg, ACTConfig):
         from lerobot.policies.act.processor_act import make_act_pre_post_processors
 
         processors = make_act_pre_post_processors(
diff --git a/src/lerobot/processor/device_processor.py b/src/lerobot/processor/device_processor.py
index dfdc80d14b..78a3ad7972 100644
--- a/src/lerobot/processor/device_processor.py
+++ b/src/lerobot/processor/device_processor.py
@@ -35,32 +35,30 @@ class DeviceProcessor(ProcessorStep):
 
     device: str = "cpu"
     float_dtype: str | None = None
-    _device: torch.device | None = None
+
+    DTYPE_MAPPING = {
+        "float16": torch.float16,
+        "float32": torch.float32,
+        "float64": torch.float64,
+        "bfloat16": torch.bfloat16,
+        "half": torch.float16,
+        "float": torch.float32,
+        "double": torch.float64,
+    }
 
     def __post_init__(self):
-        self._device = get_safe_torch_device(self.device)
-        self.device = self._device.type
+        self._device: torch.device = get_safe_torch_device(self.device)
+        self.device = self._device.type  # cuda might have changed to cuda:1
         self.non_blocking = "cuda" in str(self.device)
 
         # Validate and convert float_dtype string to torch dtype
         if self.float_dtype is not None:
-            dtype_mapping = {
-                "float16": torch.float16,
-                "float32": torch.float32,
-                "float64": torch.float64,
-                "bfloat16": torch.bfloat16,
-                "half": torch.float16,
-                "float": torch.float32,
-                "double": torch.float64,
-            }
-
-            if self.float_dtype not in dtype_mapping:
-                available_dtypes = list(dtype_mapping.keys())
+            if self.float_dtype not in self.DTYPE_MAPPING:
                 raise ValueError(
-                    f"Invalid float_dtype '{self.float_dtype}'. Available options: {available_dtypes}"
+                    f"Invalid float_dtype '{self.float_dtype}'. Available options: {list(self.DTYPE_MAPPING.keys())}"
                 )
 
-            self._target_float_dtype = dtype_mapping[self.float_dtype]
+            self._target_float_dtype = self.DTYPE_MAPPING[self.float_dtype]
         else:
             self._target_float_dtype = None
 
@@ -93,51 +91,35 @@ def _process_tensor(self, tensor: torch.Tensor) -> torch.Tensor:
         return tensor
 
     def __call__(self, transition: EnvTransition) -> EnvTransition:
-        # Create a copy of the transition
         new_transition = transition.copy()
 
-        # Process observation tensors
-        observation = transition.get(TransitionKey.OBSERVATION)
-        if observation is not None:
-            new_observation = {
-                k: self._process_tensor(v) if isinstance(v, torch.Tensor) else v
-                for k, v in observation.items()
-            }
-            new_transition[TransitionKey.OBSERVATION] = new_observation
-
-        # Process action tensor
-        action = transition.get(TransitionKey.ACTION)
-        if action is not None and isinstance(action, torch.Tensor):
-            new_transition[TransitionKey.ACTION] = self._process_tensor(action)
-
-        # Process reward tensor
-        reward = transition.get(TransitionKey.REWARD)
-        if reward is not None and isinstance(reward, torch.Tensor):
-            new_transition[TransitionKey.REWARD] = self._process_tensor(reward)
-
-        # Process done tensor
-        done = transition.get(TransitionKey.DONE)
-        if done is not None and isinstance(done, torch.Tensor):
-            new_transition[TransitionKey.DONE] = self._process_tensor(done)
-
-        # Process truncated tensor
-        truncated = transition.get(TransitionKey.TRUNCATED)
-        if truncated is not None and isinstance(truncated, torch.Tensor):
-            new_transition[TransitionKey.TRUNCATED] = self._process_tensor(truncated)
-
-        # Process complementary data tensors
-        complementary_data = transition.get(TransitionKey.COMPLEMENTARY_DATA)
-        if complementary_data is not None:
-            new_complementary_data = {}
-
-            # Process all items in complementary_data
-            for key, value in complementary_data.items():
-                if isinstance(value, torch.Tensor):
-                    new_complementary_data[key] = self._process_tensor(value)
-                else:
-                    new_complementary_data[key] = value
-
-            new_transition[TransitionKey.COMPLEMENTARY_DATA] = new_complementary_data
+        simple_tensor_keys = [
+            TransitionKey.ACTION,
+            TransitionKey.REWARD,
+            TransitionKey.DONE,
+            TransitionKey.TRUNCATED,
+        ]
+
+        dict_tensor_keys = [
+            TransitionKey.OBSERVATION,
+            TransitionKey.COMPLEMENTARY_DATA,
+        ]
+
+        # Process simple tensors
+        for key in simple_tensor_keys:
+            value = transition.get(key)
+            if isinstance(value, torch.Tensor):
+                new_transition[key] = self._process_tensor(value)
+
+        # Process dictionary-like tensors
+        for key in dict_tensor_keys:
+            data_dict = transition.get(key)
+            if data_dict is not None:
+                new_data_dict = {
+                    k: self._process_tensor(v) if isinstance(v, torch.Tensor) else v
+                    for k, v in data_dict.items()
+                }
+                new_transition[key] = new_data_dict
 
         return new_transition
 
diff --git a/src/lerobot/processor/pipeline.py b/src/lerobot/processor/pipeline.py
index a3b119356f..8ffe490d6c 100644
--- a/src/lerobot/processor/pipeline.py
+++ b/src/lerobot/processor/pipeline.py
@@ -837,6 +837,7 @@ def __repr__(self) -> str:
     def __post_init__(self):
         for i, step in enumerate(self.steps):
             if not callable(step):
+                # TODO(steven): This should instead check isinstance(step, ProcessorStep), test need to be updated
                 raise TypeError(
                     f"Step {i} ({type(step).__name__}) must define __call__(transition) -> EnvTransition"
                 )