## TL;DR

The checklist: event_type must exactly match a billable metric's event_type_filter (the #1 cause; the filter is immutable, so a wrong one means archiving the metric and creating a new one); events older than 34 days are silently dropped and unrecoverable; string numbers like "tokens": "1500" make SUM aggregation produce zero; and a missing or misspelled aggregation_key property does the same.

## Fix

1. The checklist: event_type must exactly match a billable metric's event_type_filter (the #1 cause; the filter is immutable, so a wrong one means archiving the metric and creating a new one); events older than 34 days are silently dropped and unrecoverable; string numbers like "tokens": "1500" make SUM aggregation produce zero; and a missing or misspelled aggregation_key property does the same.
   Expected: you can confirm this matches your situation.

## When to use

- You are setting up or using this Metronome feature.
- The symptom matches: sending usage events but invoice shows zero usage - silent drops.

## When NOT to use

- Unrelated Metronome issues (different feature, different failure).
- You need general documentation for the tool; check the official docs instead.

## Compatibility

Reported against Metronome. Source: https://github.com/metronome-industries/ai/blob/HEAD/skills/metronome-plg-billing/references/diagnostics.md.

## Variant phrasings

### sending usage events but invoice shows zero usage - silent drops

## Why it happens

Usage events are ingested by Metronome but the invoice shows zero usage. Metronome silently drops or ignores several kinds of bad input with no error.

## Edge cases

- If your error message differs even slightly, this is probably a different issue; search the exact text.
- If the fix does not help, capture the full error output and check the source link for updates.

## Source

https://github.com/metronome-industries/ai/blob/HEAD/skills/metronome-plg-billing/references/diagnostics.md