A change in Safari combined with a bug in HistoryHound meant that previous versions of HistoryHound would often wait much longer than they should have to update the index of your browsing history. Version 2.0.2 fixes this problem, and is also notarized by Apple to ensure its security (and compatibility with macOS 10.15 when the time comes).
You can get release notes and download links at the HistoryHound Release page.
