Group milestone missing issues

Summary

In the following situation, the milestone's view doesn't show the issue even though it has the milestone assigned.

• Group
  • Milestone 1
  • Subgroup
    • Project
      • Issue with "Milestone 1"

What is the current bug behavior?

In Milestone 1's view, the issue doesn't appear.

What is the expected correct behavior?

In Milestone 1's view, the issue should appear.

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:
Current User:   git
Using RVM:      no
Ruby Version:   2.6.3p62
Gem Version:    2.7.9
Bundler Version:1.17.3
Rake Version:   12.3.3
Redis Version:  3.2.12
Git Version:    2.22.0
Sidekiq Version:5.2.7
Go Version:     unknown
GitLab information
Version:        12.5.3
Revision:       225d2e5bb89
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     10.9
URL:            http://machine.company.com
HTTP Clone URL: http://machine.company.com/some-group/some-project.git
SSH Clone URL:  git@machine.company.com:some-group/some-project.git
Using LDAP:     yes
Using Omniauth: yes
Omniauth Providers:
GitLab Shell
Version:        10.2.0
Repository storage paths:

• default: /var/opt/gitlab/git-data/repositories GitLab Shell path: /opt/gitlab/embedded/service/gitlab-shell Git: /opt/gitlab/embedded/bin/git