clientAppUnavailable from getDetails

**Describe the bug**
After calling `await window.getDigitalGoodsService('https://play.google.com/billing')`, `getDetails(['pro'])` returns a `clientAppUnavailable` error. I Googled `"clientAppUnavailable"` and got a single result. I've poked around a bit but don't appear to have made much progress, however, I'll continue to poke around.

I've had a PWA published in the Google Play Store for close to 18 months now. With the hopeful stabilisation of the Digital Goods and Payment APIs I'm trying to add in-app play billing support. Since my TWA codebase has remained fairly stable and has aged, I re-built from scratch using bubblewrap 1.15 late last week, followed the various prompts, reinstalled android and other deps as prompted (honestly, a very sweet experience - this is amazing!!! Well done guys!) I ticked yes to billing, alpha, notifications (the other clientAppUnavailable error) etc. Built the apk. Verified asset links remained correct. Joined v1 and v2 origin programs etc.

**To Reproduce**
Steps to reproduce the behavior:
1. Bubblewrap 1.15 init
2. Accept prompts for billing, alpha features etc.
3. Digital links already in place. TWA/PWA delivered over HTTPs into newly built app
4. Configured subscriptions within Play Billing. Setup Payments profile, verified, tax status etc. All the things afaik. "pro" is the Product ID of the subscription, and it's marked active.
4. Deployed to test device.
5. Call per screen shot

6. Have made zero progress unpicking what might be going on. Also pushed a version to internal track (in addition to existing)

**Expected behavior**
Returns a list of products.

**Screenshots**
N/A

**Desktop (please complete the following information):**
- OS: Linux/WSL2
- Browser N/A
- Version: Node 16.13.1, NPM 8.1.2

**Smartphone (please complete the following information):**
- Device: Pixel 4A 5G
- OS: Android 12
- Browser: Chrome
- Version 97.0.4692.87

**Additional context**
Add any other context about the problem here.

Any pro-tips would be great! Thanks and awesome product!