## Bug description

When going to instance status > internal metrics and refreshing the dashboard, the loading fails

https://user-images.githubusercontent.com/148820/120655500-693c7480-c48b-11eb-8c75-6afd4c967506.mp4

## Expected behavior

It reloads successfully

## How to reproduce

See above

## Environment

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

## Additional context

Seems the cause is that "refresh" requests data from `/api/insight/trends` vs getting it from `/api/dashboard/id` as on first load.

Relates to #3609  

#### *Thank you* for your bug report – we love squashing them!

posthog/api/test/test_dashboard.py
item = DashboardItem.objects.create(dashboard=dashboard, filters=filter_dict, team=self.team,)
        DashboardItem.objects.create(
            dashboard=dashboard, filters=filter.to_dict(), team=self.team,
        )
        self.client.get(
            "/api/insight/trend/?events=%s&properties=%s&date_from=-7d"
            % (json.dumps(filter_dict["events"]), json.dumps(filter_dict["properties"]))
        )
        patch_response = self.client.patch(
            "/api/dashboard/%s/" % dashboard.pk, {"filters": {"date_from": "-24h"}}, format="json",
        ).json()
        self.assertEqual(patch_response["items"][0]["result"], None)
        
        response = self.client.get(
            "/api/insight/trend/?events=%s&properties=%s&date_from=-24h"
            % (json.dumps(filter_dict["events"]), json.dumps(filter_dict["properties"]))
        )
        self.assertEqual(response.status_code, 200)
        item = DashboardItem.objects.get(pk=item.pk)
        
        response = self.client.get("/api/dashboard/%s/" % dashboard.pk).json()
        self.assertEqual(len(response["items"][0]["result"][0]["days"]), 2)  
    def test_invalid_properties(self):
        properties = "invalid_json"
        response = self.client.get(f"/api/insight/trend/?properties={properties}")
        self.assertEqual(response.status_code, 400)
        self.assertDictEqual(
            response.json(), self.validation_error_response("Properties are unparsable!", "invalid_input")
        )