## 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/property.py
if not isinstance(value, List):
        value = [value]
    return [str(value).replace(" ", "") if remove_spaces else str(value) for value in value]
def get_property_values_for_key(key: str, team: Team, value: Optional[str] = None):
    parsed_date_from = "AND timestamp >= '{}'".format(relative_date_parse("-7d").strftime("%Y-%m-%d 00:00:00"))
    parsed_date_to = "AND timestamp <= '{}'".format(timezone.now().strftime("%Y-%m-%d 23:59:59"))
    if value:
        return sync_execute(
            SELECT_PROP_VALUES_SQL_WITH_FILTER.format(parsed_date_from=parsed_date_from, parsed_date_to=parsed_date_to),
            {"team_id": team.pk, "key": key, "value": "%{}%".format(value)},
        )
    return sync_execute(
        SELECT_PROP_VALUES_SQL.format(parsed_date_from=parsed_date_from, parsed_date_to=parsed_date_to),
        {"team_id": team.pk, "key": key},
    )
def filter_element(filters: Dict, prepend: str = "") -> Tuple[List[str], Dict]: