Code Owners from group is not listed in the eligible approvers MR widget

Summary

Code Owners from group are not listed in the "View eligible approvers" dropdown.

Steps to reproduce

  1. Add a group to CODEOWNERS file, example: 
    # This project is maintained by:
* @apptus/frontend
  2. Fill in merge request approvals like this: image
  3. Create a new merge request
  4. The Code Owners section shows * None

Example Project

https://gitlab.com/csvn-temp/code-owners-approvers-reproduction/merge_requests/2

The group in CODEOWNERS has 2 members, but none is shown in the MR in the "View eligible approvers" tab

What is the current bug behavior?

MR widget for approvers shows * None

What is the expected correct behavior?

MR widget for approvers shows * <Group members>

Relevant logs and/or screenshots

image

Output of checks

This bug happens on GitLab.com
12.3.0-pre 7ff5d9cd

Results of GitLab environment info

Results of GitLab application Check

Possible fixes