diff --git a/src/arcade_collection/convert/convert_to_simularium_objects.py b/src/arcade_collection/convert/convert_to_simularium_objects.py
index 55477bb..c99930b 100644
--- a/src/arcade_collection/convert/convert_to_simularium_objects.py
+++ b/src/arcade_collection/convert/convert_to_simularium_objects.py
@@ -59,4 +59,6 @@ def format_potts_for_objects(
                     name = f"{region}#{category}#{index}#{frame}"
                     data = data + [[name, int(frame), 1] + center + [[]]]
 
+            index_offset = index_offset + len(group_ids)
+
     return pd.DataFrame(data, columns=["name", "frame", "radius", "x", "y", "z", "points"])