Work through five layers in order: is the SDK loaded and initialized at all; does the track() call actually get reached in the code path; does the request leave the browser; is it blocked before Mixpanel's servers see it (ad blocker, CSP, browser privacy features); and is it landing in the wrong project (wrong token) or the right project but filtered out of the view you are checking.
Why this happens
"Events are missing" is a symptom with several independent root causes that all look identical from the reporting UI, which is why it needs a systematic checklist rather than a single fix. A missing event can mean the tracking code never ran (a conditional guard skipped it, or the component unmounted first); the SDK was not initialized yet; the request was built correctly but a client-side blocker killed it before it left the browser; it left the browser but went to the wrong project token; or the event genuinely arrived and you are looking at the wrong date range or a misspelled event-name filter.
Fix it
- Add a temporary
console.logimmediately before themixpanel.track()call and confirm it fires on a real user action, not just during development hot-reload. - Check
mixpanel.get_distinct_id()in the console to confirm the SDK is actually initialized in that session. - Open the Network tab, filter for
mixpanel.com, trigger the action, and confirm a request fires with a 200 response and the expected event name in its payload. - If no request appears at all, disable ad blockers and privacy extensions for the test and retry - this isolates client-side blocking as the cause.
- Check
mixpanel.config.token(or decode the request payload) and confirm it matches the project token you are viewing in the Mixpanel UI - cross-project token mismatches between dev/staging/prod are a common silent cause. - In the Mixpanel UI, widen the date range and double-check exact, case-sensitive event-name spelling before concluding the event never arrived - Live View has a short delay and saved reports can lag by minutes.
How to verify it worked
A successful trace ends with the exact same event name and property set appearing in Mixpanel's Live View within roughly a minute of the manual test action. If it appears in Live View but never in a saved report or funnel, the report's filter or date range - not tracking - is the remaining problem.