diff --git a/api/segment_membership/tasks.py b/api/segment_membership/tasks.py
index b8ab6709869d..3fb3d28341bf 100644
--- a/api/segment_membership/tasks.py
+++ b/api/segment_membership/tasks.py
@@ -61,6 +61,9 @@ def seed_organisation_identities(organisation_id: int) -> None:
 
     Rows are versioned at scan start via `inserted_at`
     so writes arriving mid-scan win ReplacingMergeTree dedup over the seeded row.
+
+    Identities carrying no traits at all are skipped, keeping the mirror off the
+    large populations of empty identities some environments accumulate.
     """
     log = logger.bind(organisation__id=organisation_id)
     if not settings.CLICKHOUSE_ENABLED:
@@ -104,7 +107,13 @@ def seed_organisation_identities(organisation_id: int) -> None:
                                     scan_started_at,
                                 )
                                 for doc in batch
+                                # An identity with nothing on it can only match
+                                # a segment by percentage split or `is not set`.
+                                if doc.get("identity_traits")
+                                or doc.get("system_traits")
                             ]
+                            if not rows:
+                                continue
                             # Django's CursorWrapper stub forbids dicts in
                             # the params sequence; clickhouse-driver accepts
                             # them as JSON-column payloads.
diff --git a/api/tests/unit/segment_membership/test_unit_segment_membership_tasks.py b/api/tests/unit/segment_membership/test_unit_segment_membership_tasks.py
index 2dbefed4c56a..7dacb692510b 100644
--- a/api/tests/unit/segment_membership/test_unit_segment_membership_tasks.py
+++ b/api/tests/unit/segment_membership/test_unit_segment_membership_tasks.py
@@ -151,6 +151,53 @@ def test_seed_organisation_identities__insert_fails__logs_and_continues(
     ]
 
 
+def test_seed_organisation_identities__traitless_identities__are_not_mirrored(
+    mocker: MockerFixture,
+    settings: SettingsWrapper,
+    project: Project,
+    environment: Environment,
+    segment: Segment,
+    flagsmith_identities_table: Table,
+    dynamo_identities: None,
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    enable_features("segment_membership_inspection")
+    settings.CLICKHOUSE_ENABLED = True
+    # One identity per batch, so `dave` forms a batch with nothing left to write.
+    mocker.patch.object(tasks, "_INSERT_BATCH_SIZE", 1)
+    for identifier, extra in (
+        ("dave", {}),
+        ("erin", {"system_traits": {"flagsmith_cohort_e2b1": True}}),
+    ):
+        flagsmith_identities_table.put_item(
+            Item={
+                "composite_key": f"{environment.api_key}_{identifier}",
+                "environment_api_key": environment.api_key,
+                "identifier": identifier,
+                "identity_uuid": f"f47ac10b-58cc-4372-a567-0e02b2c3d4{identifier[:2]}",
+                "identity_traits": [],
+                **extra,
+            }
+        )
+    cursor = MagicMock()
+    open_cursor = mocker.patch.object(tasks, "open_clickhouse_cursor")
+    open_cursor.return_value.__enter__.return_value = cursor
+    mocker.patch.object(tasks, "enqueue_membership_refresh")
+
+    # When
+    seed_organisation_identities(project.organisation_id)
+
+    # Then
+    # `dave` has nothing on him at all; `erin`'s cohort membership lives in
+    # `system_traits`, so she stays in the mirror.
+    payloads = [call.args[1] for call in cursor.executemany.call_args_list]
+    mirrored_identifiers = sorted(row[1] for payload in payloads for row in payload)
+    assert mirrored_identifiers == ["alice", "carol", "erin"]
+    # `dave`'s batch is skipped outright rather than written as an empty INSERT.
+    assert all(payloads)
+
+
 @pytest.mark.clickhouse
 def test_seed_organisation_identities__matching_identities__inserts_rows_versioned_at_scan_start(
     mocker: MockerFixture,
diff --git a/docs/docs/deployment-self-hosting/observability/_events-catalogue.md b/docs/docs/deployment-self-hosting/observability/_events-catalogue.md
index 6045c4df06ce..42bb898dd665 100644
--- a/docs/docs/deployment-self-hosting/observability/_events-catalogue.md
+++ b/docs/docs/deployment-self-hosting/observability/_events-catalogue.md
@@ -618,7 +618,7 @@ Attributes:
 ### `segment_membership.refresh.project.completed`
 
 Logged at `info` from:
- - `api/segment_membership/tasks.py:266`
+ - `api/segment_membership/tasks.py:275`
 
 Attributes:
  - `membership_counts.count`
@@ -628,7 +628,7 @@ Attributes:
 ### `segment_membership.refresh.project.failed`
 
 Logged at `exception` from:
- - `api/segment_membership/tasks.py:239`
+ - `api/segment_membership/tasks.py:248`
 
 Attributes:
  - `project.id`
@@ -636,8 +636,8 @@ Attributes:
 ### `segment_membership.refresh.project.skipped`
 
 Logged at `info` from:
- - `api/segment_membership/tasks.py:206`
- - `api/segment_membership/tasks.py:218`
+ - `api/segment_membership/tasks.py:215`
+ - `api/segment_membership/tasks.py:227`
 
 Attributes:
  - `project.id`
@@ -647,7 +647,7 @@ Attributes:
 ### `segment_membership.seed.environment.completed`
 
 Logged at `info` from:
- - `api/segment_membership/tasks.py:121`
+ - `api/segment_membership/tasks.py:130`
 
 Attributes:
  - `environment.id`
@@ -658,7 +658,7 @@ Attributes:
 ### `segment_membership.seed.environment.failed`
 
 Logged at `exception` from:
- - `api/segment_membership/tasks.py:114`
+ - `api/segment_membership/tasks.py:123`
 
 Attributes:
  - `environment.id`
@@ -668,9 +668,9 @@ Attributes:
 ### `segment_membership.seed.skipped`
 
 Logged at `warning` from:
- - `api/segment_membership/tasks.py:67`
- - `api/segment_membership/tasks.py:72`
- - `api/segment_membership/tasks.py:77`
+ - `api/segment_membership/tasks.py:70`
+ - `api/segment_membership/tasks.py:75`
+ - `api/segment_membership/tasks.py:80`
 
 Attributes:
  - `organisation.id`