When editing Hostgroups via Foreman, the initial edit screen loads correctly, and it's possible to make the required changes and 'Submit' them.
However the redirect back to the 'hostgroups' screen doesn't change the browser URL.

Therefore if I then try and search for a new hostgroup, I end up back at the hostgroup edit screen for the hostgroup I just changed...

The production.log shows the following:

2018-02-27 12:20:50 6de61d07 [app] [I] Started PATCH "/hostgroups/4-weareact-net-uk1a-cre-cfg" for 172.30.17.2 at 2018-02-27 12:20:50 +0000
2018-02-27 12:20:50 6de61d07 [app] [I] Processing by HostgroupsController#update as */*
2018-02-27 12:20:50 6de61d07 [app] [I]   Parameters: {"utf8"=>"✓", "authenticity_token"=>"ggdV2qfWQwKoj1Q6dNxWWWYUdw0scfytsWCXbc3Zy/F2vohv2muZGTUc/aEu5CHWxwl1cRiZtA4oodFJAxj5FQ==", "hostgroup"=>{"parent_id"=>"3", "name"=>"cfg", "description"=>"", "environment_id"=>"", "puppet_proxy_id"=>"", "puppet_ca_proxy_id"=>"", "puppetclass_ids"=>["", "409", "419"], "domain_id"=>"", "subnet_id"=>"", "realm_id"=>"", "architecture_id"=>"", "operatingsystem_id"=>"", "medium_id"=>"", "ptable_id"=>"", "pxe_loader"=>"", "id"=>"4"}, "id"=>"4-weareact-net-uk1a-cre-cfg"}
2018-02-27 12:20:50 6de61d07 [app] [I] Current user: gavin.williams (administrator)
2018-02-27 12:20:50 6de61d07 [app] [I] Redirected to https://cfg01.cre.uk1a.weareact.net/hostgroups
2018-02-27 12:20:50 6de61d07 [app] [I] Completed 302 Found in 83ms (ActiveRecord: 15.7ms)
2018-02-27 12:20:50 f4e8e52a [app] [I] Started GET "/hostgroups" for 172.30.17.2 at 2018-02-27 12:20:50 +0000
2018-02-27 12:20:50 f4e8e52a [app] [I] Processing by HostgroupsController#index as */*
2018-02-27 12:20:50 f4e8e52a [app] [I] Current user: gavin.williams (administrator)
2018-02-27 12:20:50 048bea3a [app] [I] Started GET "/node/casvc02.int.uk1a.weareact.net?format=yml" for 10.100.1.3 at 2018-02-27 12:20:50 +0000
2018-02-27 12:20:50 048bea3a [app] [I] Processing by HostsController#externalNodes as YML
2018-02-27 12:20:50 048bea3a [app] [I]   Parameters: {"name"=>"casvc02.int.uk1a.weareact.net"}
2018-02-27 12:20:50 048bea3a [app] [I] Current user: foreman_api_admin (administrator)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered common/_pagination.html.erb (1.6ms)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered hostgroups/index.html.erb within layouts/application (169.8ms)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered common/_searchbar.html.erb (8.6ms)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered layouts/_application_content.html.erb (9.3ms)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered home/_user_dropdown.html.erb (2.2ms)
2018-02-27 12:20:50 f4e8e52a [app] [I] Read fragment views/tabs_and_title_records-5 (0.1ms)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered home/_topbar.html.erb (6.9ms)
2018-02-27 12:20:50 f4e8e52a [app] [I]   Rendered layouts/base.html.erb (8.8ms)
2018-02-27 12:20:50 f4e8e52a [app] [I] Completed 200 OK in 198ms (Views: 151.6ms | ActiveRecord: 39.5ms)
2018-02-27 12:20:50 048bea3a [app] [I]   Rendered text template (0.0ms)
2018-02-27 12:20:50 048bea3a [app] [I] Completed 200 OK in 551ms (Views: 0.5ms | ActiveRecord: 22.8ms)

Let me know if can provide further info.