diff --git a/airflow-core/src/airflow/api_fastapi/core_api/services/ui/grid.py b/airflow-core/src/airflow/api_fastapi/core_api/services/ui/grid.py
index acf333c64a884..5b20511d31f47 100644
--- a/airflow-core/src/airflow/api_fastapi/core_api/services/ui/grid.py
+++ b/airflow-core/src/airflow/api_fastapi/core_api/services/ui/grid.py
@@ -98,28 +98,26 @@ def _find_aggregates(
             "type": "mapped_task",
             "parent_id": parent_id,
             **_get_aggs_for_node(mapped_details),
+            "details": mapped_details,
         }
 
         return
     if isinstance(node, SerializedTaskGroup):
-        children = []
+        children_details = []
         for child in get_task_group_children_getter()(node):
             for child_node in _find_aggregates(node=child, parent_node=node, ti_details=ti_details):
                 if child_node["parent_id"] == node_id:
-                    children.append(
-                        {
-                            "state": child_node["state"],
-                            "start_date": child_node["min_start_date"],
-                            "end_date": child_node["max_end_date"],
-                        }
-                    )
+                    # Collect detailed task instance data from all children
+                    if child_node.get("details"):
+                        children_details.extend(child_node["details"])
                 yield child_node
         if node_id:
             yield {
                 "task_id": node_id,
                 "type": "group",
                 "parent_id": parent_id,
-                **_get_aggs_for_node(children),
+                **_get_aggs_for_node(children_details),
+                "details": children_details,
             }
         return
     if isinstance(node, SerializedBaseOperator):
@@ -128,5 +126,6 @@ def _find_aggregates(
             "type": "task",
             "parent_id": parent_id,
             **_get_aggs_for_node(details),
+            "details": details,
         }
         return
diff --git a/airflow-core/tests/unit/api_fastapi/core_api/routes/ui/test_grid.py b/airflow-core/tests/unit/api_fastapi/core_api/routes/ui/test_grid.py
index 93b5ecfa48794..9bd06f764d5ad 100644
--- a/airflow-core/tests/unit/api_fastapi/core_api/routes/ui/test_grid.py
+++ b/airflow-core/tests/unit/api_fastapi/core_api/routes/ui/test_grid.py
@@ -598,7 +598,7 @@ def test_grid_ti_summaries_group(self, session, test_client):
                     "min_start_date": None,
                 },
                 {
-                    "child_states": {"success": 2},
+                    "child_states": {"success": 4},
                     "max_end_date": "2025-03-02T00:00:12Z",
                     "min_start_date": "2025-03-02T00:00:04Z",
                     "state": "success",
@@ -671,7 +671,7 @@ def sort_dict(in_dict):
                 "state": None,
             },
             {
-                "child_states": {"running": 1},
+                "child_states": {"success": 1, "running": 1, "None": 1},
                 "max_end_date": "2024-12-30T01:02:03Z",
                 "min_start_date": "2024-12-30T01:00:00Z",
                 "state": "running",
@@ -692,14 +692,14 @@ def sort_dict(in_dict):
                 "min_start_date": None,
             },
             {
-                "child_states": {"None": 2},
+                "child_states": {"None": 6},
                 "task_id": "task_group",
                 "max_end_date": None,
                 "min_start_date": None,
                 "state": None,
             },
             {
-                "child_states": {"None": 1},
+                "child_states": {"None": 2},
                 "task_id": "task_group.inner_task_group",
                 "max_end_date": None,
                 "min_start_date": None,