Automatic $exposure tracking

Hello Amplitude SDK Team,

[We](https://www.carbmanager.com/) are trying to implement Amplitude Experiments in our app but having trouble understanding how the automatic`$exposure` tracking works!

The [docs](https://www.docs.developers.amplitude.com/experiment/general/exposure-tracking/#automatic-exposure-tracking) say that the exposure tracking works automatically when using the SDK (we use version `1.5.3`)

We need the `$exposure` to be tracked by Amplitude along with a custom event tracking provider.

Here is a snippet of how we initialize the SDK

```js
AmplitudeExperiment.initialize(apiKey, {
automaticExposureTracking: true,
exposureTrackingProvider: new RudderStackExposureTrackingProvider(), // our custom provider
debug:
true,
initialVariants: experiments.getAll().reduce(
(variantsAcc, experiment) => ({
...variantsAcc,
[experiment.id]: experiment.fallback,
}),
{}
),
});
```

We are unable to see the exposure events being tracked in Amplitude

We would appreciate any help with this.

Thank you
Joel