A test user subscription purchase fails with an 'Item Not Available' error (code 1891831) when attempting to purchase a subscription through the Manage Test User Subscriptions tab in the Monetization dashboard. The subscription has a $0.99/month plan after a 7-day free trial, appears in the Subscriptions list, and has a SKU set. The test user has test payment information configured. The error message states 'Sorry, this item isn't setup for purchases yet. Please try again later.' The failure occurs immediately upon attempting the purchase, with Trace ID D52vhu0zTUD returned with the error.