Firebase storage emulator ignored by go admin sdk

I'm trying to setup the storage emulator for my firebase project. I am using the Go admin sdk. However it seems to be ignored despite following the documented process.

App initialization:

func App(ctx context.Context) (*firebase.App, error) {
    opt := option.WithCredentialsFile("firebase-service-account.json")
    config := firebase.Config{
        StorageBucket: "<my-project-id>.appspot.com",
    }
    app, err := firebase.NewApp(ctx, &config, opt)
    if err != nil {
        return nil, fmt.Errorf("error initializing app: %v", err)
    }
    return app, nil
}

.env file loaded on startup:

FIRESTORE_EMULATOR_HOST="localhost:8081"
FIREBASE_STORAGE_EMULATOR_HOST="localhost:9199"
GCLOUD_PROJECT="my-project-id"

I also tried manually setting these by running: export FIREBASE_STORAGE_EMULATOR_HOST="localhost:9199" and export GCLOUD_PROJECT="my-project-id".

However, when when writing to the default bucket, my blob appears in the actual firestore console for storage, not the storage emulator.

I pulled the GCLOUD_PROJECT value from my service account json file, the project_id field specifically. Also confirmed that 9199 is the port that storage is running on.

Besides setting those FIREBASE_STORAGE_EMULATOR_HOST and GCLOUD_PROJECT am I missing something else?