The Sentry `Dedupe` integration has been filtering out our events, even
when they were never sent due to our `beforeSend` handler. It was
wrongly identifying them as duplicates because it has no knowledge of
`beforeSend` or whether they were actually sent or not.
To resolve this, the filtering we were doing in `beforeSend` has been
moved to a Sentry integration. This integration is installed ahead of
the `Dedupe` integration, so `Dedupe` should never find out about any
events that we filter out, and thus will never consider them as sent
when they were not.
Mark Stacey
1f36ba4b75