Web analytics conversion sometimes don't show in the overview query

Bug Description

Bug description

The overview query can sometimes show 0 unique and total conversions, but the graph below shows conversions. These 2 queries should match

This was reported here https://posthoghelp.zendesk.com/agent/tickets/21134 (moved to PostHog: https://us.posthog.com/project/2/support/tickets/23870)

How to reproduce

This doesn't seem to affect the posthog org, but it has affected some customers with these steps to reproduce:

1. Open web analytics
2. Add a conversion goals
3. Observe that total and unique conversions are zero

Additional context

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables or https://eu.posthog.com/settings/project-details#variables]
- [ ] PostHog Hobby self-hosted with `docker compose`, version/commit: [please provide]
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]

The issue names no files or tests; start by tracing the web analytics overview query and the graph query from the reproduction steps. Compare their conversion results and verify that total and unique conversions match after adding a conversion goal.