diff --git a/src/axolotl/utils/collators/batching.py b/src/axolotl/utils/collators/batching.py
index 5a514b613..b68a31d71 100644
--- a/src/axolotl/utils/collators/batching.py
+++ b/src/axolotl/utils/collators/batching.py
@@ -182,7 +182,7 @@ class FlexBatchSamplerDataCollatorForSeq2Seq(DataCollatorForSeq2Seq):
         collated_seq_lens, max_seq_len = get_seqlens_from_pos_ids(out["position_ids"])
         # out["attention_mask"] = packed_block_causal_mask(collated_seq_lens)
         out["attention_mask"] = create_block_causal_mask(collated_seq_lens, max_seq_len)
-
+        raise ValueError(f"{out['attention_mask'].shape}")
         return out