Amplify Console - custom domain shows different content than default url

After a successful deployment of our Angular app to our "prod" hosting environment, the changes are showing successfully in the default amplifyapp url (e.g. https://prod.1234567.amplifyapp.com) but NOT in our Route53 custom domain.

We've tried rebundling/redeploying a number of times with the same result. Wondering if there's an issue with the underlying CloudFront caching (we don't manage our own distribution), or if this is related to the way we configured the custom domain (although previous deployments have worked fine - this issue just arose today).

Any idea what we can do to fix this?