At present, Error is shown only if host fails to save due to Network interface issue or it shows inline errors. But there are cases where host fails to save due to wrong selection of Lifecycle environment or content view where it silently fails to save the host and only show error in production log. For example, if you specify the wrong lifecycle environment and deploy via foreman_proxy "Content view environment content facets is invalid" appears in production.log but nothing is displayed in GUI and it simply didn't save the host.