some of my problem triggers are quite long-living. sometimes triggers can stay in a problem state more than a month or even longer.
when housekeeper gets rid of events table data older than such triggers age, these triggers disappear from "Last N issues" dashboard table, while being visible through Monitoring/Triggers view.
I find this behaviour erroneous and propose a simple but working patch against 1.8.6 frontend. 1.9.x branch include/blocks.inc.php/make_latest_issue() is different from 1.8.x version, but the principle stays the same.