## Bug description
I added an event (that exists) to an action, and now my action hangs forever.

I added an insight viewed event

w/ filters `insight == RETENTION` and `same_retention_and_cohortizing_event = false` – this appears to have broken my action where it does not load and I cannot edit it.

Cannot reproduce this same behavior locally.


## Expected behavior
- The action loads if the schema is correct.
-  If there's erroneous data it should load and let me edit it.

## How to reproduce

1. Create an action on Posthog cloud, in our main app
2. Add 'insight viewed' with filters `insight == RETENTION` and `same_retention_and_cohortizing_event = false`
3. The action will spin forever

## Environment

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

## Additional context

[Sentry error](https://sentry.io/organizations/posthog/issues/2378948964/?project=1899813&referrer=slack)

Console errors 
<img width="1607" alt="Screen Shot 2021-05-03 at 5 45 39 PM" src="https://user-images.githubusercontent.com/5965891/116950024-b0d7a280-ac38-11eb-93c8-245390240532.png">
<img width="1167" alt="Screen Shot 2021-05-03 at 5 51 34 PM" src="https://user-images.githubusercontent.com/5965891/116950026-b208cf80-ac38-11eb-96e1-6a8f018f650a.png">



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

ee/clickhouse/models/test/test_action.py
def test_filter_event_exact_url(self):
        event_target = _create_event(
            event="$autocapture",
            team=self.team,
            distinct_id="whatever",
            properties={"$current_url": "https://posthog.com/feedback/123"},
        )
        _create_event(
            event="$pageview",
            team=self.team,
            distinct_id="whatever",
            properties={"$current_url": "https://posthog.com/feedback/123"},
        )
        _create_event(
            event="$autocapture",
            team=self.team,
            distinct_id="whatever",
            properties={"$current_url": "https://posthog.com/feedback/1234"},
        )
        action1 = Action.objects.create(team=self.team, name="action1")
        step1 = ActionStep.objects.create(
            event="$autocapture", action=action1, url="https://posthog.com/feedback/123", url_matching=ActionStep.EXACT,
        )
        query, params = filter_event(step1)
        full_query = "SELECT uuid FROM events WHERE {}".format(" AND ".join(query))
        result = sync_execute(full_query, {**params, "team_id": self.team.pk})
        self.assertEqual(str(result[0][0]), event_target.pk)
    def test_filter_event_contains_url(self):