Amplify Console not showing backend selection for previews

### Before opening, please confirm:

- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-console/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-console/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-console/blob/master/CONTRIBUTING.md).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

### App Id

d3qhqw00lnenwe

### Region

eu-west-1

### Amplify Console feature

Previews

### Describe the bug

When trying to select an existing backend environment for use with PR previews, there appears no dropdown where I can select an environment, even after waiting a long time.


### Expected behavior

A dropdown appears to select a backend environment.

### Reproduction steps

1. Open Amplify Console > Previews
2. Select "develop" branch and hit "Manage"
3. Select "Point all Pull Requests for this branch to an existing environment".

### Build Settings

_No response_

### Additional information

_No response_

Reproduce the issue in Amplify Console for app d3qhqw00lnenwe in eu-west-1. Open Previews, manage the develop branch, and choose the option to point pull requests to an existing environment. Done means a backend-environment dropdown appears and allows an existing environment to be selected.

Written by the indexing model from the issue text.