## Bug description

If I mark an insight as a favorite (⭐) and then refresh, the insight is no longer marked as a favorite although it is (can see it in Favorites).

<img width="390" alt="image" src="https://user-images.githubusercontent.com/30181361/182802236-9ecf0531-899c-4f25-ae86-bc233cefdc2f.png">

Note that I'm in the _Favorites_ tab and that _Bug example_ is not starred.
## Environment

- [x] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: please provide

posthog/api/test/test_insight.py
response_nonexistent_property = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id': '$pageview'}])}&properties={json.dumps([{'type':'event','key':'foo','value':'barabarab'}])}"
        )
        response_nonexistent_cohort = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id': '$pageview'}])}&properties={json.dumps([{'type':'cohort','key':'id','value':2137}])}"
        )  # 
        response_nonexistent_property_data = response_nonexistent_property.json()
        response_nonexistent_cohort_data = response_nonexistent_cohort.json()
        response_nonexistent_property_data.pop("last_refresh")
        response_nonexistent_cohort_data.pop("last_refresh")
        self.assertEntityResponseEqual(
            response_nonexistent_property_data["result"], response_nonexistent_cohort_data["result"]
        )  # 
    def test_cohort_without_match_group_works(self):
        whatever_cohort_without_match_groups = Cohort.objects.create(team=self.team)
        response_nonexistent_property = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id': '$pageview'}])}&properties={json.dumps([{'type':'event','key':'foo','value':'barabarab'}])}"
        )
        response_cohort_without_match_groups = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id':'$pageview'}])}&properties={json.dumps([{'type':'cohort','key':'id','value':whatever_cohort_without_match_groups.pk}])}"
        )  # 
        self.assertEqual(response_nonexistent_property.status_code, 200)
        response_nonexistent_property_data = response_nonexistent_property.json()
        response_cohort_without_match_groups_data = response_cohort_without_match_groups.json()
        response_nonexistent_property_data.pop("last_refresh")
        response_cohort_without_match_groups_data.pop("last_refresh")
        self.assertEntityResponseEqual(
            response_nonexistent_property_data["result"], response_cohort_without_match_groups_data["result"]
        )  # 
    def test_precalculated_cohort_works(self):