Why Our Meta Pixel Lead Event Disappeared — and What Four Failures Taught Us

We added a Meta Pixel Lead event to track a key user action. We deployed, opened Test Events in Meta Events Manager, and saw nothing. What followed was a chain of four failures that ended up shaping how we write tracking code at ReplyQ.

The setup: tracking across two pages

The event could not fire on the form page itself — the user navigates away immediately after submit. Classic approach: save a flag, fire the event on the destination page. Simple in theory. We fell four times.

Failure 1: fbq event_callback is not reliable

Meta's fbq supports a callback that fires when the event reaches Meta's servers. Our plan: wait for the callback, then navigate. Problem: the callback does not always fire — especially behind ad blockers and on slow connections. We dropped this approach entirely.

Failure 2: router.push breaks cross-page tracking

We switched to the sessionStorage flag pattern:

sessionStorage.setItem('signup_success', '1')
router.push('/destination')

Still nothing. The reason: in Next.js App Router, router.push is soft navigation — the URL changes but the page does not reload. A useEffect that already ran does not re-run. The fix:

window.location.href = '/destination'

Hard navigation. Full page reload. useEffect fires fresh. sessionStorage survives the transition.

Failure 3: fbq async load race condition

With hard navigation and sessionStorage in place — still nothing. Browser console showed typeof window.fbq === 'undefined' at useEffect mount time. The Pixel script loads asynchronously and was not ready yet.

Solution — a retry loop:

const fireLead = () => {
  attempts++
  if (typeof window.fbq !== 'function') {
    if (attempts < 10) setTimeout(fireLead, 200)
    return
  }
  window.fbq('track', 'Lead', { ... })
  sessionStorage.removeItem('signup_success') // clean up AFTER firing
}
fireLead()

Key detail: clean the flag only after a successful fire, never before. Cleaning first means a retry is impossible if fbq fails.

Failure 4: a second signup path nobody audited

After all three fixes — still failing. Console logged:

Lead skipped - no signup marker

sessionStorage empty. No query param. How?

A single grep across the codebase:

grep -r "/destination-page" src/

Revealed two separate signup flows. The email/password path had all the fixes. The OAuth path called an older helper that did router.push('/destination') with no marker at all. The user was coming through OAuth. Every flag check was correctly failing because the flag was never set.

We fixed the OAuth path and added a third fallback:

const fromQuery   = params.get('signup_success') === '1'
const fromSession = sessionStorage.getItem('signup_success') === '1'
const fromReferrer = document.referrer.includes('/signup')
const shouldFire  = fromQuery || fromSession || fromReferrer

Three rules we kept

• Grep before every tracking fix. Always count how many code paths reach the destination page. One missed path breaks everything.
• router.push breaks cross-page tracking in Next.js App Router. For any event that needs to survive a page transition — use window.location.href.
• Three fallbacks beat one. query param + sessionStorage + referrer. If one fails, another saves the event.

The Lead event landed exactly as expected. The path to get there taught us more than a first-try success ever would have.

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