Harden Mode exclusions still not working in Avast 2014.9.0.2018, Windows 8.1 x64.
The first entry could only be added via Harden Mode popup. Manual entries were not remembered (The executable with poor reputation continued to trigger a Harden Mode popup after selecting ‘OK’ via GUI)
Subsequent entries were not present regardless of method of exclusion added.
Edit: Tested with Harden Mode Moderate