Mailchimp Block: no audience groups being displayed under the "Mailchimp Groups" heading in the sidebar

### Impacted plugin

Jetpack

### Quick summary

While Mailchimp allows someone to self-categorize which group they want to be added to when signing up to a mailing list, the Mailchimp Block is designed to show the associated audience groups under the "Mailchimp Groups" heading in the sidebar. For some reason, the block doesn't seem to be pulling in any groups from Mailchimp even though the user has successfully connected their account to Mailchimp

### Steps to reproduce

1. Create a form with audience groups in Mailchimp
2. Connect Mailchimp account to WordPress.com account
3. Add Mailchimp Block to a page or post
4. Click on Mailchimp Block in editor, and look under the "Mailchimp Groups" heading in the sidebar

### A clear and concise description of what you expected to happen.

I expected the audience groups added in Mailchimp to be listed under the "Mailchimp Groups" heading on the sidebar

### What actually happened

The audience groups the user added in Mailchimp aren't showing up under the "Mailchimp Groups" heading in the sidebar

### Impact

One

### Available workarounds?

No but the platform is still usable

### If the above answer is "Yes...", outline the workaround.

User could upgrade to a Business Plan. After doing that, they could use the Mailchimp plugin or the custom HTML provided on the Mailchimp website

### Platform (Simple and/or Atomic)

Simple

### Logs or notes

_No response_

Start with the Mailchimp Block and the editor sidebar section labeled “Mailchimp Groups.” Reproduce the steps in the issue using a connected Mailchimp account with audience groups; trace why the groups are not displayed. Done means those groups appear in the sidebar after the account is connected.

Written by the indexing model from the issue text.