diff --git a/semantica/conflicts/source_tracker.py b/semantica/conflicts/source_tracker.py
index d2035c66..9ae19aa9 100644
--- a/semantica/conflicts/source_tracker.py
+++ b/semantica/conflicts/source_tracker.py
@@ -614,8 +614,8 @@ class SourceTracker:
                 if item_type == "entity":
                     entity_id = item.get("entity_id")
                     if entity_id:
-                        entry = self.track_entity_source(entity_id, source_ref, **metadata)
-                        if entry is not None:
+                        ok = self.track_entity_source(entity_id, source_ref, **metadata)
+                        if ok:
                             stats["entities_tracked"] += 1
                             stats["total_tracked"] += 1
                         else:
@@ -628,10 +628,10 @@ class SourceTracker:
                     property_name = item.get("property_name")
                     value = item.get("value")
                     if entity_id and property_name is not None:
-                        entry = self.track_property_source(
+                        ok = self.track_property_source(
                             entity_id, property_name, value, source_ref, **metadata
                         )
-                        if entry is not None:
+                        if ok:
                             stats["properties_tracked"] += 1
                             stats["total_tracked"] += 1
                         else:
@@ -642,10 +642,10 @@ class SourceTracker:
                 elif item_type == "relationship":
                     relationship_id = item.get("relationship_id")
                     if relationship_id:
-                        entry = self.track_relationship_source(
+                        ok = self.track_relationship_source(
                             relationship_id, source_ref, **metadata
                         )
-                        if entry is not None:
+                        if ok:
                             stats["relationships_tracked"] += 1
                             stats["total_tracked"] += 1
                         else:
diff --git a/semantica/split/provenance_tracker.py b/semantica/split/provenance_tracker.py
index e5d0edb4..e4cd2096 100644
--- a/semantica/split/provenance_tracker.py
+++ b/semantica/split/provenance_tracker.py
@@ -97,6 +97,9 @@ class ProvenanceTracker:
         self.store_metadata = config.get("store_metadata", True)
         self.track_versions = config.get("track_versions", False)
 
+        self._provenance_store: Dict[str, ProvenanceInfo] = {}
+        self._chunk_registry: Dict[str, str] = {}  # chunk_id -> provenance_id
+
         # Determine whether to use unified backend
         use_unified = config.get("use_unified", True) and UNIFIED_AVAILABLE
         
@@ -110,8 +113,6 @@ class ProvenanceTracker:
             # Fallback to legacy in-memory storage
             self._unified_manager = None
             self._use_unified = False
-            self._provenance_store: Dict[str, ProvenanceInfo] = {}
-            self._chunk_registry: Dict[str, str] = {}  # chunk_id -> provenance_id
             self.logger.debug("Chunk provenance tracker initialized with legacy backend")
 
     def track_chunk(
@@ -147,7 +148,7 @@ class ProvenanceTracker:
             # Delegate to unified manager
             try:
                 chunk_metadata = {**chunk.metadata, **metadata, "chunk_size": len(chunk.text)} if self.store_metadata else metadata
-                self._unified_manager.track_chunk(
+                entry = self._unified_manager.track_chunk(
                     chunk_id=chunk_id,
                     source_document=source_document,
                     source_path=source_path,
@@ -156,6 +157,9 @@ class ProvenanceTracker:
                     parent_chunk_id=parent_chunk_id,
                     **chunk_metadata
                 )
+                if entry is None:
+                    self.logger.warning("Unified tracking failed (returned None), using fallback")
+                    return self._track_chunk_legacy(chunk, source_document, source_path, parent_chunk_id, **metadata)
                 return chunk_id  # Return chunk_id for compatibility
             except Exception as e:
                 self.logger.warning(f"Unified tracking failed, using fallback: {e}")
@@ -303,7 +307,7 @@ class ProvenanceTracker:
                         version=prov.get("version", "1.0"),
                         timestamp=prov.get("timestamp")
                     )
-                return None
+                return self._get_provenance_legacy(chunk_id)
             except Exception as e:
                 self.logger.warning(f"Unified retrieval failed, using fallback: {e}")
                 return self._get_provenance_legacy(chunk_id)
diff --git a/tests/conflicts/test_conflicts.py b/tests/conflicts/test_conflicts.py
index 8018cb4c..34dad4d2 100644
--- a/tests/conflicts/test_conflicts.py
+++ b/tests/conflicts/test_conflicts.py
@@ -103,7 +103,7 @@ class TestConflictsModule(unittest.TestCase):
                 "source": self.source2,
             },
         ]
-        with patch.object(tracker, "track_property_source", return_value=None):
+        with patch.object(tracker, "track_property_source", return_value=False):
             stats = tracker.track_sources_batch(source_data)
             self.assertEqual(stats["properties_tracked"], 0)
             self.assertEqual(stats["total_tracked"], 0)
diff --git a/tests/provenance/test_backward_compat.py b/tests/provenance/test_backward_compat.py
index 16268aeb..cb785e5b 100644
--- a/tests/provenance/test_backward_compat.py
+++ b/tests/provenance/test_backward_compat.py
@@ -141,6 +141,22 @@ class TestSplitProvenanceBackwardCompat:
         
         assert len(prov_ids) == 3
 
+    def test_unified_tracking_returns_none_triggers_fallback(self):
+        """Test that when _unified_manager.track_chunk returns None, fallback provenance is stored (#783)."""
+        from unittest.mock import patch
+        tracker = SplitProvenanceTracker()
+        chunk = Chunk(text="Test chunk for none fallback", start_index=0, end_index=10, metadata={})
+        
+        with patch.object(tracker._unified_manager, "track_chunk", return_value=None):
+            prov_id = tracker.track_chunk(chunk, source_document="doc_1")
+            assert prov_id is not None
+            # Confirm it fell back to legacy store and is retrievable
+            assert chunk.id in tracker._chunk_registry
+            assert prov_id in tracker._provenance_store
+            prov_info = tracker.get_provenance(chunk.id)
+            assert prov_info is not None
+            assert prov_info.source_document == "doc_1"
+
 
 class TestNoProvenanceOverhead:
     """Test that provenance has zero overhead when not used."""