On the dashboard, when the filter "Unacknowledged only" is active, as soon as you acknowledge a problem where another trigger is depending on, that depending trigger will show up as a problem.
"Host-2 unreachable" depends on "Host-1 unreachable". Host status shows "Host-1 unreachable". When you acknowledge that issue, Host status now starts showing "Host-2 unreachable". Expected is that "Host-2 unreachable" remains hidden as it does on other parts of the front-end.