EventHint extra does nothing when using captureMessage

I’m using the PHP SDK and the captureMessage function. This is what I’ve got:

            EventHint::fromArray(['extra' => $context])

But no matter what I send as the EventHint extra parameter, it doesn’t show up in Sentry. I stepped through in XDebug to make sure it’s being set correctly, and everything looks fine; it’s setting the EventHint::$extra property correctly. The message is showing up in Sentry just fine, and the severity is correct, but the extra information simply doesn’t show up anywhere.

Am I missing something?