diff --git a/runtime/databricks/automl_runtime/forecast/deepar/model.py b/runtime/databricks/automl_runtime/forecast/deepar/model.py
index 137c37a..5c13e4a 100644
--- a/runtime/databricks/automl_runtime/forecast/deepar/model.py
+++ b/runtime/databricks/automl_runtime/forecast/deepar/model.py
@@ -100,7 +100,7 @@ def predict(self,
 
         pred_df = pred_df.rename(columns={'index': self._time_col})
         if self._id_cols:
-            id_col_name = '-'.join(self._id_cols)
+            id_col_name = self._id_cols[0]
             pred_df = pred_df.rename(columns={'item_id': id_col_name})
         else:
             pred_df = pred_df.drop(columns='item_id')
diff --git a/runtime/databricks/automl_runtime/forecast/deepar/utils.py b/runtime/databricks/automl_runtime/forecast/deepar/utils.py
index 016de93..fbf6475 100644
--- a/runtime/databricks/automl_runtime/forecast/deepar/utils.py
+++ b/runtime/databricks/automl_runtime/forecast/deepar/utils.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-from typing import List, Optional
+from typing import List, Optional, Union, Dict
 
 import pandas as pd
 
-
 def validate_and_generate_index(df: pd.DataFrame, 
                                 time_col: str, 
                                 frequency_unit: str, 
@@ -66,10 +65,12 @@ def validate_and_generate_index(df: pd.DataFrame,
 
     return new_index_full
 
-def set_index_and_fill_missing_time_steps(df: pd.DataFrame, time_col: str,
-                                          frequency_unit: str,
-                                          frequency_quantity: int,
-                                          id_cols: Optional[List[str]] = None):
+def set_index_and_fill_missing_time_steps(
+        df: pd.DataFrame, time_col: str,
+        frequency_unit: str,
+        frequency_quantity: int,
+        id_cols: Optional[List[str]] = None
+) -> Union[pd.DataFrame, Dict[any, pd.DataFrame]]:
     """
     Transform the input dataframe to an acceptable format for the GluonTS library.
 
@@ -95,14 +96,16 @@ def set_index_and_fill_missing_time_steps(df: pd.DataFrame, time_col: str,
     valid_index = validate_and_generate_index(df=df, time_col=time_col, frequency_unit=frequency_unit, frequency_quantity=frequency_quantity)
 
     if id_cols is not None:
+        if len(id_cols) > 1:
+            raise ValueError("DeepAR does not support multiple time series id columns")
         df_dict = {}
         for grouped_id, grouped_df in df.groupby(id_cols):
             if isinstance(grouped_id, tuple):
-                ts_id = "-".join([str(x) for x in grouped_id])
-            else:
-                ts_id = str(grouped_id)
-            df_dict[ts_id] = (grouped_df.set_index(time_col).sort_index()
-                              .reindex(valid_index).drop(id_cols, axis=1))
+                # TODO (ML-52171): Fix the DeepAR library to support multi-time series id columns
+                # For now, DeepAR is dropped for multiple id_cols
+                raise ValueError("DeepAR does not support multiple time series id columns")
+            df_dict[grouped_id] = (grouped_df.set_index(time_col).sort_index()
+                                   .reindex(valid_index).drop(id_cols, axis=1))
 
         return df_dict