Katello 3.1.0, Foreman 1.12
CentOS 7, x86_64

Attempting to create a Host Group yields the following in production.log:

2016-09-07 09:35:57 [app] [I] Started POST "/hostgroups" for 192.168.16.139 at 2016-09-07 09:35:57 -0500
2016-09-07 09:35:57 [app] [I] Processing by HostgroupsController#create as */*
2016-09-07 09:35:57 [app] [I]   Parameters: {"utf8"=>"✓", "authenticity_token"=>"XuYd4yd0auuvXO3gXhjEq7z8poy8qfW0NQ9nk8h+mFKmTiPAMf0iAwjOjVXM6xvjBCV3FUG04b/18rfENECbGQ==", "hostgroup"=>{"parent_id"=>"1", "name"=>"TG - Home - Development - CentOS 6 - Core", "lifecycle_environment_id"=>"3", "content_view_id"=>"18", "environment_id"=>"5", "content_source_id"=>"", "puppet_ca_proxy_id"=>"", "puppet_proxy_id"=>"", "openscap_proxy_id"=>"", "config_group_ids"=>["", "1"], "puppetclass_ids"=>[""], "domain_id"=>"", "subnet_id"=>"", "realm_id"=>"", "architecture_id"=>"1", "operatingsystem_id"=>"5", "medium_id"=>"9", "ptable_id"=>"96", "root_pass"=>"[FILTERED]", "group_parameters_attributes"=>{"1473258957498"=>{"name"=>"kt_activation_keys", "value"=>"[FILTERED]", "hidden_value"=>"[FILTERED]", "_destroy"=>"kt_activation_keys"}}, "location_ids"=>["", "2"], "organization_ids"=>["", "1"], "id"=>""}, "media_selector"=>"install_media", "kt_activation_keys"=>"CentOS 6 - Development"}
2016-09-07 09:35:57 [app] [I] Failed to save: Taxable taxonomies is invalid, Taxable taxonomies is invalid
2016-09-07 09:35:58 [app] [I]   Rendered config_groups/_config_group.html.erb (99.2ms)
2016-09-07 09:35:58 [app] [I]   Rendered config_groups/_config_group.html.erb (48.4ms)
2016-09-07 09:35:58 [app] [I]   Rendered config_groups/_config_groups_selection.html.erb (168.7ms)
2016-09-07 09:35:58 [app] [I]   Rendered puppetclasses/_selectedClasses.html.erb (0.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered puppetclasses/_classes_in_groups.html.erb (3.8ms)
2016-09-07 09:35:58 [app] [I]   Rendered puppetclasses/_classes.html.erb (19.8ms)
2016-09-07 09:35:58 [app] [I]   Rendered puppetclasses/_class_selection.html.erb (259.2ms)
2016-09-07 09:35:58 [app] [I]   Rendered common/os_selection/_architecture.html.erb (3.9ms)
2016-09-07 09:35:58 [app] [I]   Rendered common/os_selection/_operatingsystem.html.erb (153.1ms)
2016-09-07 09:35:58 [app] [I]   Rendered common/os_selection/_initial.html.erb (159.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered puppetclasses/_class_parameters.html.erb (43.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered puppetclasses/_classes_parameters.html.erb (55.5ms)
2016-09-07 09:35:58 [app] [I]   Rendered common_parameters/_inherited_parameters.html.erb (0.3ms)
2016-09-07 09:35:58 [app] [I]   Rendered common_parameters/_parameter.html.erb (1.6ms)
2016-09-07 09:35:58 [app] [I]   Rendered common_parameters/_parameter.html.erb (1.2ms)
2016-09-07 09:35:58 [app] [I]   Rendered common_parameters/_parameters.html.erb (4.5ms)
2016-09-07 09:35:58 [app] [I]   Rendered taxonomies/_loc_org_tabs.html.erb (11.9ms)
2016-09-07 09:35:58 [app] [I]   Rendered hostgroups/_form.html.erb (603.3ms)
2016-09-07 09:35:58 [app] [I]   Rendered hostgroups/new.html.erb within layouts/application (603.8ms)
2016-09-07 09:35:58 [app] [I]   Rendered layouts/_application_content.html.erb (0.3ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_user_dropdown.html.erb (2.8ms)
2016-09-07 09:35:58 [app] [I] Read fragment views/tabs_and_title_records-3 (0.1ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_organization_dropdown.html.erb (15.4ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_location_dropdown.html.erb (14.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_org_switcher.html.erb (33.4ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (3.5ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (7.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (0.8ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (313.5ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (2.6ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (1.5ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_submenu.html.erb (2.7ms)
2016-09-07 09:35:58 [app] [I] Write fragment views/tabs_and_title_records-3 (5.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered home/_topbar.html.erb (386.0ms)
2016-09-07 09:35:58 [app] [I]   Rendered layouts/base.html.erb (386.9ms)
2016-09-07 09:35:58 [app] [I] Completed 200 OK in 1092ms (Views: 963.5ms | ActiveRecord: 39.4ms)