1. Create a new Product
2. Add the default Echo API Backend
3. Add an Application Plan and Publish
4. Navigate to Product > Integration > Configuration ... Promote APICast to v1.0 to Staging and then to Production
5. The icon turns ON denoting Configuration is outdated - without any additional config change
6. Try promoting staging again - and nothing changes to this icon

Strangely what works is - delete and re-add backend to the product. And then promote APICast to staging

When the user makes any additional change, e.g. Edit Backend, Add new Policies etc - which genuinely triggers a "Config Outdated" event .. and then promotes that change, it works just fine.
The error seems to happen only the first time the user promotes with no new config changes.