Group board assignee scope stuck on single user, unable to set to "Any assignee"

Summary

Version: 12.0.1-ee Self Hosted

I updated the assignee scope of a group board to a single user. Now I'm unable to change it back to the default "Any assignee"

Steps to reproduce

Screencast_26-06-19_15_15_41

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:		Ubuntu 18.04
Proxy:		no
Current User:	git
Using RVM:	no
Ruby Version:	2.6.3p62
Gem Version:	2.7.9
Bundler Version:1.17.3
Rake Version:	12.3.2
Redis Version:	3.2.12
Git Version:	2.21.0
Sidekiq Version:5.2.7
Go Version:	unknown
GitLab information
Version:	12.0.1-ee
Revision:	3a5f14fef4e
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	10.7
URL:		https://projects.lovefurniture.ie
HTTP Clone URL:	https://projects.lovefurniture.ie/some-group/some-project.git
SSH Clone URL:	git@projects.lovefurniture.ie:some-group/some-project.git
Elasticsearch:	no
Geo:		no
Using LDAP:	no
Using Omniauth:	yes
Omniauth Providers:
GitLab Shell
Version:	9.3.0
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

Results of GitLab application Check

Expand for output related to the GitLab application check

Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 9.3.0 ? ... OK (9.3.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK
Access to /var/opt/gitlab/.ssh/authorized_keys: OK
gitlab-shell self-check successful
Checking GitLab Shell ... Finished
Checking Gitaly ...
Gitaly: ... default ... OK
Checking Gitaly ... Finished
Checking Sidekiq ...
Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1
Checking Sidekiq ... Finished
Checking Incoming Email ...
Incoming Email: ... Checking Reply by email ...
IMAP server credentials are correct? ... yes
Init.d configured correctly? ... skipped
MailRoom running? ... skipped
Checking Reply by email ... Finished
Checking Incoming Email ... Finished
Checking LDAP ...
LDAP: ... LDAP is disabled in config/gitlab.yml
Checking LDAP ... Finished
Checking GitLab App ...
Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... no
Try fixing it:
sudo chown -R git /var/opt/gitlab/gitlab-rails/uploads
sudo find /var/opt/gitlab/gitlab-rails/uploads -type f -exec chmod 0644 {} ;
sudo find /var/opt/gitlab/gitlab-rails/uploads -type d -not -path /var/opt/gitlab/gitlab-rails/uploads -exec chmod 0700 {} ;
For more information see:
doc/install/installation.md in section "GitLab"
Please fix the error above and rerun the checks.
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
11/1 ... yes
11/2 ... yes
2/3 ... yes
11/4 ... yes
2/5 ... yes
2/8 ... yes
11/10 ... yes
2/11 ... yes
6/12 ... yes
2/13 ... yes
2/14 ... yes
2/15 ... yes
2/18 ... yes
2/19 ... yes
2/20 ... yes
2/21 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.21.0 ? ... yes (2.21.0)
Git user has default SSH configuration? ... no
Try fixing it:
mkdir ~/gitlab-check-backup-1561558817
sudo mv /var/opt/gitlab/.ssh/id_rsa ~/gitlab-check-backup-1561558817
sudo mv /var/opt/gitlab/.ssh/id_rsa.pub ~/gitlab-check-backup-1561558817
For more information see:
doc/ssh/README.md in section "SSH on the GitLab server"
Please fix the error above and rerun the checks.
Active users: ... 3
Elasticsearch version 5.6 - 6.x? ... skipped (elasticsearch is disabled)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished