diff --git a/src/wagtail_personalisation/models.py b/src/wagtail_personalisation/models.py
index 3df7731..f1e1a1a 100644
--- a/src/wagtail_personalisation/models.py
+++ b/src/wagtail_personalisation/models.py
@@ -169,6 +169,10 @@ class Segment(ClusterableModel):
 
         if self.is_static:
             request = RequestFactory().get('/')
+
+            rules = self.get_rules()
+            all_static = all(rule.static for rule in rules)
+
             for session in Session.objects.filter(
                 expire_date__gt=timezone.now(),
             ).iterator():
@@ -176,7 +180,8 @@ class Segment(ClusterableModel):
                 user = user_from_data(session_data.get('_auth_id'))
                 request.user = user
                 request.session = SessionStore(session_key=session.session_key)
-                if all(rule.test_user(request) for rule in self.get_rules() if rule.static):
+                all_pass = all(rule.test_user(request) for rule in rules if rule.static)
+                if rules and all_static and all_pass:
                     self.sessions.add(session)
 
 
diff --git a/tests/unit/test_static_dynamic_segments.py b/tests/unit/test_static_dynamic_segments.py
index 7815d8e..b70b806 100644
--- a/tests/unit/test_static_dynamic_segments.py
+++ b/tests/unit/test_static_dynamic_segments.py
@@ -17,14 +17,34 @@ def test_session_added_to_static_segment_at_creation(rf, site, client):
 
     segment = SegmentFactory(type=Segment.TYPE_STATIC)
     VisitCountRule.objects.create(counted_page=site.root_page, segment=segment)
+    segment.save()
 
     assert session.session_key in segment.sessions.values_list('session_key', flat=True)
 
 
+@pytest.mark.django_db
+def test_mixed_static_dynamic_session_doesnt_generate_at_creation(rf, site, client):
+    session = client.session
+    session.save()
+    client.get(site.root_page.url)
+
+    segment = SegmentFactory(type=Segment.TYPE_STATIC)
+    VisitCountRule.objects.create(counted_page=site.root_page, segment=segment)
+    TimeRule.objects.create(
+        start_time=datetime.time(0, 0, 0),
+        end_time=datetime.time(23, 59, 59),
+        segment=segment,
+    )
+    segment.save()
+
+    assert not segment.sessions.all()
+
+
 @pytest.mark.django_db
 def test_session_not_added_to_static_segment_after_creation(rf, site, client):
     segment = SegmentFactory(type=Segment.TYPE_STATIC)
     VisitCountRule.objects.create(counted_page=site.root_page, segment=segment)
+    segment.save()
 
     session = client.session
     session.save()
@@ -37,6 +57,7 @@ def test_session_not_added_to_static_segment_after_creation(rf, site, client):
 def test_session_added_to_static_segment_after_creation(rf, site, client):
     segment = SegmentFactory(type=Segment.TYPE_STATIC, count=1)
     VisitCountRule.objects.create(counted_page=site.root_page, segment=segment)
+    segment.save()
 
     session = client.session
     session.save()
@@ -49,6 +70,7 @@ def test_session_added_to_static_segment_after_creation(rf, site, client):
 def test_session_not_added_to_static_segment_after_full(rf, site, client):
     segment = SegmentFactory(type=Segment.TYPE_STATIC, count=1)
     VisitCountRule.objects.create(counted_page=site.root_page, segment=segment)
+    segment.save()
 
     session = client.session
     session.save()
@@ -65,12 +87,18 @@ def test_session_not_added_to_static_segment_after_full(rf, site, client):
 
 
 @pytest.mark.django_db
-def test_sessions_not_added_to_static_segment_if_rule_not_static():
+def test_sessions_not_added_to_static_segment_if_rule_not_static(client, site):
+    session = client.session
+    session.save()
+    client.get(site.root_page.url)
+
     segment = SegmentFactory(type=Segment.TYPE_STATIC)
     TimeRule.objects.create(
-        start_time=datetime.time(8, 0, 0),
-        end_time=datetime.time(23, 0, 0),
-        segment=segment)
+        start_time=datetime.time(0, 0, 0),
+        end_time=datetime.time(23, 59, 59),
+        segment=segment,
+    )
+    segment.save()
 
     assert not segment.sessions.all()
 
@@ -83,6 +111,7 @@ def test_does_not_calculate_the_segment_again(rf, site, client, mocker):
 
     segment = SegmentFactory(type=Segment.TYPE_STATIC, count=2)
     VisitCountRule.objects.create(counted_page=site.root_page, segment=segment)
+    segment.save()
 
     mock_test_rule = mocker.patch('wagtail_personalisation.adapters.SessionSegmentsAdapter._test_rules')
     client.get(site.root_page.url)