diff --git a/example_trainer/data.py b/example_trainer/data.py
index be7667c2..e79fecb0 100644
--- a/example_trainer/data.py
+++ b/example_trainer/data.py
@@ -237,11 +237,28 @@ def get_data(
         - inference_logprob_batches are aligned with labels for proper GRPO loss computation
     """
     batches = []
+    _logged_logprob_warning = False
     
     while True:
         data = get_batch(url=atropos_url)
         
         if data["batch"] is not None:
+            # DEBUG: Check if inference_logprobs exists in the data
+            if not _logged_logprob_warning:
+                has_logprobs = any("inference_logprobs" in item for item in data["batch"])
+                if has_logprobs:
+                    # Check if they're non-empty
+                    sample_item = next((item for item in data["batch"] if "inference_logprobs" in item), None)
+                    if sample_item and sample_item.get("inference_logprobs"):
+                        sample_lp = sample_item["inference_logprobs"][0] if sample_item["inference_logprobs"] else []
+                        print(f"    [Data] ✓ inference_logprobs found in batch (sample len: {len(sample_lp)})")
+                    else:
+                        print(f"    [Data] ⚠ inference_logprobs key exists but is empty!")
+                else:
+                    print(f"    [Data] ⚠ NO inference_logprobs in batch data!")
+                    print(f"    [Data] Keys in first item: {list(data['batch'][0].keys())}")
+                _logged_logprob_warning = True
+            
             # Save batch for debugging
             with open("temp.json", "w", encoding="utf-8") as f:
                 json.dump(data, f)
diff --git a/example_trainer/training.py b/example_trainer/training.py
index 69ff1d9f..f36e9b63 100644
--- a/example_trainer/training.py
+++ b/example_trainer/training.py
@@ -214,6 +214,18 @@ def compute_grpo_loss(
         # Move inference logprobs to correct device/dtype
         ref_logprobs = inference_logprobs.to(logp_per_token.device, logp_per_token.dtype)
         
+        # DEBUG: Check if inference logprobs look valid
+        with torch.no_grad():
+            ref_nonzero = (ref_logprobs != 0).float()
+            ref_nonzero_frac = (ref_nonzero * mask).sum() / mask.sum()
+            ref_mean = (ref_logprobs * mask).sum() / mask.sum()
+            train_mean = (logp_per_token * mask).sum() / mask.sum()
+            if ref_nonzero_frac < 0.5:
+                print(f"    [WARNING] Only {ref_nonzero_frac*100:.1f}% of inference logprobs are non-zero!")
+                print(f"    [WARNING] This suggests inference_logprobs field may be missing from data")
+            if abs(ref_mean - train_mean) > 1.0:
+                print(f"    [DEBUG] Large logprob gap: ref_mean={ref_mean:.3f}, train_mean={train_mean:.3f}")
+        
         # Compute importance sampling ratio: π(a|s) / π_old(a|s) = exp(log π - log π_old)
         log_ratio = logp_per_token - ref_logprobs
         ratio = torch.exp(log_ratio)