Rejection because subscriptions unavailable at time of review

This is the first subscription submission for this existing/distributed app.

This is the rejection message:

Specifically, your app did not load any subscription offers at launch and no further content could be accessed.

The app works correctly in simulator, on device and TestFlight. I am using a sync'd StoreKit configuration file.

The app has no functionality at all without the subscription being available to the app. It seems the app is being tested independently of the subscription upon first launch. Or said differently, the app is being tested without a subscription being available because the subscription has not been approved and available at the time the app is first launched for testing.

It seems the reviewers aren't making the subscription available at the time of launching the app for testing as is the case in XCode, on device and within TestFlight - the subscription is always available in those environs.

Is my analysis correct, close, a mile off or ...?

Thanks for your help and insight.